Chevrolet Volt

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Chevrolet Volt
DCA 06 2012 Chevy Volt 4035.JPG
2012 Chevrolet Volt
Overview
Manufacturer General Motors
Also called
Production December 2010 – present
Model years 2011–present
Assembly United States: Detroit, Michigan (Detroit/Hamtramck Assembly)
Designer Bob Boniface
Body and chassis
Class Compact car (C-segment)
Body style 5-door hatchback
Layout Transverse front-engine, front-wheel drive
Platform GM Delta II
Related Cadillac ELR
Powertrain
Engine
Electric motor
  • 1x 111 kW (149 hp)
  • 1x 55 kW (74 hp)
  • permanent magnet motor/generators
Transmission Voltec 4ET50 Multi-mode electric transaxle
Hybrid drivetrain Series hybrid (GM Voltec)[2]
Battery
  • 16.0 kWh lithium-ion (2011/12)
  • 16.5 kWh lithium-ion (2013/14)
  • 17.1 kWh lithium-ion (2015)[3]
Range 380 miles (610 km) (EPA) (2011/14)[4]
Electric range
  • 35 miles (56 km) (EPA) (2011/12)
  • 38 miles (61 km) (2013/14)[4]
  • 52 miles (83 km) (NEDC)
Plug-in charging 120V/15A, 240V/20A AC[5]
Dimensions
Wheelbase 2,685 mm (105.7 in)[1]
Length 4,498 mm (177.1 in)
Width 1,788 mm (70.4 in)
Height 1,438 mm (56.6 in)
Curb weight 1,721 kg (3,794 lb)

The Chevrolet Volt is a plug-in hybrid manufactured by General Motors, also marketed in rebadged variants as the Holden Volt in Australia and New Zealand, and with a different fascia as the Vauxhall Ampera in the United Kingdom and as the Opel Ampera in the remainder of Europe.

Sales of the 2011 Volt began in the U.S. in mid-December 2010 followed by various European countries and other international markets in 2011. As of May 2015, the Volt and Ampera models have combined global sales of about 93,000 units, with the U.S. as the leading market with almost 78,000 Volts delivered since its introduction in 2010. As of April 2015, over 9,700 Opel/Vauxhall Ampera cars had been sold in Europe. The Netherlands is the world's second largest Volt/Ampera market, and leads the European region with almost 5,000 Amperas and over 1,000 Volts registered. The Volt was the top selling plug-in electric car in the United States until February 2015. The Volt/Ampera family of vehicles is the world's all-time best-selling plug-in hybrid vehicle as of May 2015.

The Volt operates as a pure battery electric vehicle until its battery capacity drops to a predetermined threshold from full charge. From there its internal combustion engine powers an electric generator to extend the vehicle's range as needed. When the engine is running it may be periodically mechanically linked (by a clutch) to a planetary gear set, and hence the output drive axle, to improve energy efficiency. The Volt's regenerative braking also contributes to the on-board electricity generation. Under the United States Environmental Protection Agency (EPA) cycle, the 2013/14 model year Volt all-electric range is 38 mi (61 km), with a combined electric mode/gasoline-only rating of 62 mpg-US (3.8 L/100 km; 74 mpg-imp) equivalent (MPG-equivalent).

The Volt has won several awards, including the 2009 Green Car Vision Award, 2011 Green Car of the Year, 2011 North American Car of the Year, 2011 World Green Car and 2012 European Car of the Year. Controversies regarding the Volt include the extent to which the U.S. federal government may have participated in the Volt’s development, which continued through General Motors' 2009 government-led bankruptcy,[6][7][8] and concerns about the battery pack fire risk following a crash test that the National Highway Traffic Safety Administration (NHTSA) performed on a Volt in 2011.[7][8][9] At the completion of its investigation NHTSA concluded that no discernible defect trend exists.[10][11]

The second generation Volt was officially unveiled at the January 2015 North American International Auto Show. Its improved battery system and drivetrain increased the Volt all-electric range to 50 mi (80 km), and its fuel economy in charge-sustaining mode to 41 mpg-US (5.7 L/100 km; 49 mpg-imp).[12] Retail sales are scheduled to begin in the second half of 2015 as a 2016 model year.[13]

Terminology

Further information: Hybrid vehicle drivetrain

The Society of Automotive Engineers' (SAE) definition of a hybrid vehicle states that the vehicle shall have "two or more energy storage systems both of which must provide propulsion power, either together or independently."[14] General Motors has avoided the use of the term "hybrid" when describing its Voltec designs, even after the carmaker revealed that in some cases the combustion engine provided some assist at high speeds or to improve performance.[15] Instead General Motors describes the Volt as an electric vehicle equipped with a "range extending" gasoline powered internal combustion engine (ICE) as a genset and therefore dubbed the Volt an "Extended Range Electric Vehicle" or E-REV.[16][17] In a January 2011 interview, the Chevy Volt's Global Chief Engineer, Pamela Fletcher, referred to the Volt as "an electric car with extended range."[18]

Basic powertrain configuration of a series hybrid vehicle, one of the two possible modes of the Chevrolet Volt when operated as range-extender vehicle

According to the Society of Automotive Engineers (SAE) definitions, the Volt is a plug-in hybrid vehicle, due to the combination of an internal combustion engine and two electric motors, along with a battery that can accept off-board energy.[19] The Volt operates as a purely electric vehicle for the first 25 to 50 miles (40 to 80 km) in charge-depleting mode. When the battery capacity drops below a pre-established threshold from full charge, the vehicle enters charge-sustaining mode, and the Volt's control system will select the most optimally efficient drive mode to improve performance and boost high-speed efficiency.[19][20]

History

Concept vehicle

The Chevrolet Volt concept car debuted at the January 2007 North American International Auto Show, becoming the first-ever series plug-in hybrid concept car shown by a major car manufacturer.[21][22] The Volt concept vehicle had four doors with a rear liftgate and seating for four passengers. This was a significant change in design when compared to the General Motors EV1 of the 1990s, which only seated two to reduce weight and to make the necessary room for the lead-acid battery pack. The top speed was also increased on the Volt, from the electronically limited 80 miles per hour (130 km/h) to 100 miles per hour (160 km/h). The battery pack size was reduced, from about 10.6 cu ft (300 L) in volume in the EV1, to 3.5 cu ft (100 L) in the Volt.[21][23]

Then General Motors' Vice Chairman Robert Lutz said the two-seater sports car being developed by Tesla, the Tesla Roadster, and the rapid advancement of lithium-ion battery technology inspired him to push the carmaker to develop the Volt after the 2006 Detroit Auto Show.[24][25][26] Lutz's initial idea was to develop an all-electric car, but Jon Lauckner, General Motors Vice President for Global Vehicle Development, convinced him that to avoid an expensive battery, range anxiety concerns, and lack of public charging infrastructure, they could use a smaller battery pack with a small gasoline engine driving a generator acting as a backup to extend the range, but without a mechanical connection between the gasoline engine and the drive wheels, so it would be a pure electrically driven vehicle without many of the limitations General Motors learned from the EV1 experience.[25]

The Chevrolet Volt concept car was unveiled at the January 2007 North American International Auto Show

Most of the Volt initial design parameters defined for the development of the concept car, then referred as the "iCar" in homage to the iPod, were kept throughout the process up to the final production version. A key design parameter was a target of 40 miles (64 km) for the all-electric range, selected to keep the battery size small and lower costs, and mainly because research showed that in the U.S. 78 percent of daily commuters travel 40 miles or less. This target range would allow most travel to be accomplished electrically driven and the assumption was made that charging will take place at home overnight. This requirement translated using a lithium-ion battery pack with an energy storage capacity of 16 kWh considering that the battery would be used until the state of charge (SOC) of the battery reached 30%. This limit to the SOC was necessary in order to maintain operational performance under a wide range of environments, and to minimize the battery degradation to allow at least a ten-year life span. The initial target range for the gasoline engine/generator was set between 250 to 300 miles (400 to 480 km) and the vehicle had to be family size for four or five passengers.[25][27]

Another key design decision was to develop the concept car based on a new family of common powertrain components for electric propulsion, which initially was called the E-Flex Systems, “E” stands for electric drive and “Flex” for the different sources of electricity, but later was renamed Voltec drive system. The E-Flex or Voltec powertrain is an attempt to standardize many components of possible future electrically propelled vehicles, and to allow multiple interchangeable electricity-generating systems. The E-Flex powertrain has the potential to adapt the vehicles to pure battery electric, to fuel cell-powered or to several other sources of energy to create electricity on board, such as engine-generator sets (genset) fueled by gasoline, diesel, biodiesel, ethanol fuel (E100), or flex-fuel (E85). Regenerative braking would also contribute to the on-board electricity generation.[22][28][29] On October 2006 the E-flex powertrain was selected for the new propulsion architecture and the name Volt was chosen by General Motors.[28]

The Volt concept car became the first application of the E-Flex (Voltec) drive system with a combination of an electric motor, the same used in the Chevrolet Equinox Fuel Cell, a 16 kW·h (58 MJ) lithium-ion battery pack with 136 kW of peak power, and a genset consisting of a small 1.0 L, 3-cylinder turbocharged flex-fuel capable engine linked to a 53 kW (71 hp) generator. General Motors called this genset an electric vehicle (EV) range extender. The vehicle was propelled by an electric motor with a peak output of 120 kW (160 hp) delivering 236 lb-ft (320 N-m) of motoring torque. The concept car featured several advanced materials from GE Automotive Plastics which allowed GM to reduce the vehicle weight up to 50 percent.

The Volt concept featured a 12 US gal (45 L; 10.0 imp gal) fuel capacity providing the vehicle a total driving range of around 640 mi (1,030 km), which considered a gasoline fuel efficiency of about 50 mpg-US (4.7 L/100 km; 60 mpg-imp) and a 40 mi (64 km) all-electric range. According to General Motors estimates, a daily drive of 60 mi (97 km), combined with an overnight recharge to support the first 40 all-electric miles, would yield an effective gasoline fuel economy of 150 mpg-US (1.6 L/100 km; 180 mpg-imp).[22][29] General Motors also emphasized that the Volt would further reduce dependence on imported oil if E85 ethanol was used instead of gasoline to power the on-board generator engine. Robert Lutz added that if the driver used E85, "the fuel economy figure became 525 miles per (equivalent) petroleum gallon", as only 15% of gasoline is used in this blend.[30][31] General Motors also noted that actual production of the Volt depended on further battery development, because the required rechargeable batteries needed to make the Volt a viable vehicle did not exist in the market and had yet to be developed.[22][25][31] The concept car was actually powered by two 12-volt conventional car batteries, just enough power to allow the vehicle to move at low speeds in the stand.[32]

First generation (2010–2015)

Production model

The production design model officially unveiled on September 16, 2008, as part of General Motors centennial celebration at the Wintergarden headquarters in Detroit.[33] The production model differed greatly in design from the original concept car. The carmaker cited necessary aerodynamic changes needed to reduce the concept car's high drag coefficient of Cd=0.43[34] down to a more efficient Cd=0.28,[35] though still somewhat higher than the Toyota Prius Cd=0.25. Another reason was the use of General Motors' new global compact vehicle platform Delta II to keep costs reasonable, and shared with the 2010 model year Chevrolet Cruze.[36] Another significant difference from the concept car is the seating, as the production Volt seats four rather than five passengers. This change was due to the higher-than-usual central tunnel that runs from the front console to the rear seat that houses the car's T-shaped battery pack.[37]

First production version of the Chevrolet Volt at the 2008 Australian International Motor Show

After the concept was put into the pipeline for production, General Motors began looking for a partner to develop the Volt's lithium-ion battery pack. The carmaker evaluated about twenty-five different battery cell chemistries and constructions from around two dozen lithium-ion battery makers around the world.[38] Due to their more promising cell technologies, two companies were selected in June 2007, Compact Power (CPI), which uses a lithium manganese oxide (LiMn2O4) cell made by its parent company, LG Chemical; and Continental Automotive Systems, which uses lithium iron phosphate based cylindrical cells made by A123Systems.[38][39][40] By the end of October 2007 CPI (LG Chem) delivered their finished battery pack prototypes, and A123 delivered theirs by January 2008. General Motors testing process was conducted at the laboratory the carmaker had created for the GM EV1 program. The battery packs included monitoring systems designed to keep the batteries cool and operating at optimum capacity despite a wide range of ambient temperatures.[38][40] In order to make sure the battery pack would last ten years and 150,000 miles (240,000 km) expected for the battery warranty, the Volt team decided to use only half of the 16 kWh capacity to reduce the rate of capacity degradation, limiting the state of charge (SOC) up to 80% of capacity and never depleting the battery below 30%.[40][41] General Motors also was expecting the battery could withstand 5,000 full discharges without losing more than 10% of its charge capacity.[40]

In April 2008 General Motors started extensive battery testing. In two years the carmaker put the battery packs to the equivalent of 150,000 real-world miles (240,000 km) and ten years of use.[40] The durability of the battery pack was tested for a broad range of extreme ambient conditions including a shaker table to simulate potholes and a thermal chamber, to simulate temperatures varying from 116 °F (47 °C), typical of the Southwest deserts, to −40 °F (−40 °C) typical of the Alaska tundra.[38] In April 2008 the lithium-ion battery pack was placed in Chevrolet Malibus fitted with the Volt powertrain to be used as test mules for further real-world testing.[40][42] In October 2008 General Motors chose CPI (LG Chemical) to provide the battery systems for the first production version of the Volt.[43][44] In July 2008 General Motors confirmed that a non-turbocharged, 1.4 L 4-cylinder engine would be used as the range extender, and that the intention was to build it in Flint, Michigan.[45] In April 2009, General Motors allowed journalists to test the Volt powertrain in the body of Chevrolet Cruze sedans used as test mules which lacked the range-extending generator at the GM Technical Center in Warren, Michigan.[46]

Final production vehicle, the 2011 Chevrolet Volt

The first pre-production test car based on the final Volt design was built in June 2009, in Warren, Michigan,[47][48] and by October 2009, 80 Volts had been built and were tested under various conditions.[48][49] On March 31, 2010, the first factory-built Volt was produced at the Detroit Hamtramck Assembly Plant in order to test the production line and for quality control purposes, both of the tooling and the pre-production vehicles produced before regular production began.[50][51]

Tony Posawatz was the Volt Vehicle Line Director from 2006 to 2012,[52] and he was known as employee #1 and led the team from concept to production.[53]

Official introduction

General Motors held a ceremony at its Detroit Hamtramck Assembly Plant on November 30, 2010, to introduce the first Chevrolet Volt off the assembly line. The first Volt built for retail sale was earmarked for display at General Motors' Heritage Center museum in Sterling Heights, Michigan.[54] The second unit was offered at a public auction, with an opening bid of US$50,000 and it was won by Rick Hendrick who paid US$225,000. The proceeds went to fund math and sciences education in Detroit through the Detroit Public Schools Foundation.[55] Deliveries to retail customers in the United States began in mid December 2010.[56] Volt deliveries began in Canada in September 2011.[57] The first deliveries of the Chevrolet Volt in Europe took place in November 2011.[58][59] The European version of the Volt, the Opel Ampera, was released to retail customers in Europe in February 2012.[60] Deliveries of the right-hand drive Vauxhall Ampera in the UK began in May 2012.[58] The Holden Volt was released in Australia in December 2012.[61]

Specifications

Drivetrain

Right side: power inverter on top of the electric motor used for traction; left side: the 1.4 L gasoline engine used as a generator to keep the battery at minimum charge.

The 2011 Chevrolet Volt has a 16 kWh / 45 A·h (10.4 kWh usable) lithium-ion battery pack that can be charged by plugging the car into a 120-240 VAC residential electrical outlet using the provided SAE J1772-compliant charging cord. No external charging station is required.[62] The Volt is propelled by an electric motor with a peak output of 111 kW (149 hp) delivering 273 lb·ft (370 N·m) of torque. Capacity of the battery pack was increased to 16.5 kWh (10.9 kWh usable) for 2013 models, which increased the all-electric range from 35 to 38 mi (56 to 61 km). Other specifications remained the same. The battery pack capacity was increased to 17.1 kWh for 2015 models. This incremental upgrade is likely to reflect in an improvement in range over previous model years, but as of July 2014, the 2015 Volt has not been re-certified with the EPA.[3]

While driving, after the Volt battery has dropped to a predetermined threshold from full charge, a small naturally aspirated 1.4 L 4-cylinder gasoline fueled internal combustion engine (Opel's Family 0[63]) with approximately 80 hp (60 kW), powers a 55 kW generator to extend the Volt's range. The vehicle also has a regenerative braking system. The electrical power from the generator is sent primarily to the electric motor, with the excess going to the batteries, depending on the state of charge (SOC) of the battery pack and the power demanded at the wheels.[1][64]

The Volt requires premium gasoline with a minimum 91 or octane rating[65] because the higher octane rating fuel permits the 10.5:1 compression ratio engine to utilize more ignition timing advance in order to maximize its fuel efficiency by 5 to 10% as compared to regular gasoline.[66][67] For users who drive mostly in electric mode and to avoid maintenance problems caused by storing the same gasoline in the tank for months, the 2011 Volt has a sealed and pressurized fuel tank to avoid evaporation, and as a result, the fuel filler has to be depressurized before opening the tank. Also the engine management system monitors the time between engine running and it is programmed to prompt the driver to run past the 40-mile (64 km) all-electric range before recharging in order to consume some gasoline. If the driver does not run on gasoline, the system will automatically run the maintenance mode which starts the engine to consume some of the aging fuel and circulate the fluids within the engine.[68] A configuration with an E85 flex-fuel capable engine is under development and was expected to be available in 2013.[19]

Powertrain cut-away of the Volt showing both engines and the underfloor T shape tunnel where the battery pack is located
The Volt seats four people as the battery runs down the center of the car preventing a rear bench
Operating and driving modes

The Voltec drivetrain has three power converting elements:[69]

  • Primary traction electric motor/generator, provides good acceleration for driving at lower speeds and regeneration for braking, its maximum output of 111 kW setting the maximum output of the whole system.
  • Secondary electric motor/generator, works primarily as generator capable of producing 55 kW or when necessary acts as a motor assisting the primary electric motor.[70]
  • Internal combustion engine of 63 kW power,[71] engaged when the batteries reach the predetermined threshold.

These units are connected via a planetary gear and three electrically controlled hydraulic clutches to provide power output for propulsion in any of four programmed operating modes:[69]

  1. Single motor electric - The primary motor runs solely on battery power, maximum propulsion power is 111 kW.
  2. Dual motor electric - At higher vehicle speeds the secondary motor engages over the planetary gear such that it reduces the speed of the primary motor. This facilitates higher efficiency and better mileage for the combined system, without increasing the maximum power.
  3. Single motor extended - The battery reaches its minimum charge which triggers the combustion engine. The engine drives the secondary motor which now works as a generator, via the charging electronics, to keep the minimum battery charge level. The primary motor can still provide its 111 kW for short acceleration, albeit not sustained.
  4. Dual motor extended - The electric motors are used again in dual configuration with increased efficiency at higher speeds. Additionally the gasoline engine contributes propulsion power via the planetary gear. While power is drained from the battery the amount is less than in mode 2 for the same propulsion power, thus extending the range.

The drivetrain permits the Volt to operate as a pure battery electric vehicle until its battery capacity has been depleted to a defined level, at which time it commences to operate as a series hybrid design where the gasoline engine drives the generator, which keeps the battery at minimum level charge and provides power to the electric motors. The full charge of the battery is replenished only by loading it on the electrical grid.
While in this series mode at higher speeds and loads, (typically above 30 miles per hour (48 km/h) at light to moderate loads) the gasoline engine can engage mechanically to the output from the transmission and assist both electric motors in driving the wheels, in which case the Volt operates as a power-split or series-parallel hybrid. After its all-electric range has been depleted, at speeds between 30 to 70 miles per hour (48 to 113 km/h), the Volt is programmed to select the most efficient drive mode, which improves performance and boosts high-speed efficiency by 10 to 15 percent.[19][72]

While operating modes are switched automatically the Volt allows the driver to choose from three drive modes: normal, sport and mountain. The mountain mode, which is expected to be required only under unusual power demand conditions, increases minimum battery state of charge (SOC) to around 45%, thus maintaining performance on steep and long grades. The driver will hear more engine noise due to the higher rate of power generation required to maintain this mode.[72] The sport mode causes the engine to rev higher, and the response to the throttle pedal is quicker.[73] The Ampera has an additional option, the "City Mode" or "battery hold", allowing the driver to save the energy currently stored in the battery for use when traveling in urban areas or restricted zones.[74][75] The 2013 model year Volt includes a "Hold" option to provide the same choice.[76]

Battery

The 2011 Volt's lithium-ion battery (Li-ion) battery pack weighs 435 lb (197 kg) and "consists of 288 individual cells arranged into nine modules. Plastic frames hold pairs of lithium-ion cells that sandwich an aluminum cooling fin. The design and construction of that aluminum plate was critical to ensuring an even temperature distribution with no hot or cool spots across the flat, rectangular cell. The battery pack has its own cooling circuit that is similar to, but independent from, the engine cooling system."[64][77]

Inlet for the electrical charger in the left side of the Chevrolet Volt with the manufacturer's provided charging cord

For the 2011/2012 model years, the battery pack stores 16 kWh of energy but it is controlled or buffered via the energy management system to use only 10.3 kWh of this capacity to maximize the life of the pack. For this reason the battery pack never fully charges or depletes, as the software only allows the battery to operate within a state of charge (SOC) window of 65%, after which the engine kicks in and maintains the charge near the lower level. The minimum SOC varies depending on operating conditions. When more power is required, such as mountain mode, the lower limit of the SOC will rise to 45% to ensure there is enough power available.[64][72] The battery capacity was increased to 16.5 kWh for the 2013 model year, the SOC window will be increased to use 10.8 kWh of the total battery energy, and the buffer to ensure battery life will not be reduced. These changes will increase the Volt's all-electric range but charging will take slightly longer. The improved battery performance and durability were achieved through minor changes to the material composition of the battery cell chemistry.[76][78]

Despite containing near identical energy (+/- 0.5 kWh), the Volt's battery pack is over 70% lighter than the EV1's original 1,310 lb (590 kg), 16.5 kWh AC Delco lead-acid battery pack, mainly because the Volt uses higher specific energy Li-ion batteries. Li-ion batteries are expected to become less expensive as economies of scale take effect.[79][80][81]

Because batteries are sensitive to temperature changes, the Volt has a thermal management system to monitor and maintain the battery cell temperature for optimum performance and durability. The Volt's battery pack provides reliable operation, when plugged in, at cell temperatures as low as −13 °F (−25 °C) and as high as 122 °F (50 °C).[64][82][83] The Volt features a battery pack that can be both warmed or cooled. In cold weather the battery coolant is electrically heated during charging or operation in order to provide full power capability; in hot weather the battery coolant can be chilled utilizing the vehicle's air-conditioning system preventing over-temperature damage.[64][82][84]

The Volt's battery is guaranteed by General Motors for eight years or 100,000 miles (160,000 km), and will cover all 161 battery components.[82][85] GM estimates that the Volt batteries will degrade by 10 to 30% after 8 years or 100,000 miles.[86] GM has applied for a patent that may allow technicians to quickly and cheaply recover some of the performance of degraded battery packs.[87] The Volt’s battery management system runs more than 500 diagnostics at 10 times per second, allowing it to keep track of the Volt’s battery pack in real-time, 85% of which ensure the battery pack is operating safely and 15% monitor battery performance and life.[82]

The Volt uses a plug specification published in 2009, SAE J1772-2009, that is considered a standard for electric cars in North America.[62] Depending on in-car settings a full charge will take approximately 10 hours (12A setting) to as much as 14 hours (8A setting) from a standard North American 120 V, 15 A outlet and about 4 hours from a 240 VAC source and suitable 240V EVSE. The Volt comes with a 20 ft (6.1 m) charging cord suitable for the standard household power outlet in its country of sale. If plugged in, recharging can be controlled remotely through a smartphone application.[64]

Others

In order to save energy, the Volt will sometimes heat the seats instead of blowing heated air through HVAC system, as heating the vehicle's cabin draws significant power, and can even exceed what is needed to move the vehicle on occasions.[88] A power-saving stereo system uses amplifiers that switch on and off rapidly to save power. It uses 50 percent less energy. The system is also lighter because the use of high grade neodymium magnets.[88]

Performance

The Volt has a top speed of 100 mph (160 km/h).[19] According to Edmunds.com road tests, the Volt's 0 to 60 mph (0–97 km/h) acceleration time is 9.2 seconds running on electric-only mode, and 9.0 seconds with the gasoline engine assisting propulsion.[89] Motor Trend reports the Volt's quarter mile (402 m) time is 16.9 sec @ 84.3 mph (135.7 km/h),[90] while Edmunds reports a quarter mile (402 m) time of 16.8 sec @ 81.5 mph (131.2 km/h) in electric-only operation, and 16.6 sec @ 85.5 mph (137.6 km/h) with the gasoline engine assisting.[89] Motor Trend reports a 60 to 0 mph (97 to 0 km/h) braking distance of 112 ft (34 m) and Edmunds.com of 124 ft (38 m).[89][90]

Range

United States
Monroney label showing EPA's fuel economy and environmental comparison label for the 2013 Chevrolet Volt
2011/2012 model year

According to General Motors the Volt's all-electric range with fully charged batteries varies from 25 to 50 miles (40 to 80 km) depending on terrain, driving technique, and temperature.[19][91] The Environmental Protection Agency (EPA) official all-electric range is 35 miles (56 km) with an energy consumption of 36 kWh per 100 miles (810 kJ/km). This range is based on the agency's five-cycle tests using varying driving conditions and climate controls. The total range with a full tank of gasoline and a fully charged battery is 379 miles (609.9 km) according to EPA tests.[92][93]

The Volt's nominal usable battery capacity is 10.3 kWh. The Volt's fuel tank capacity is 9.3 US gallons (35 L; 7.7 imp gal). Aside from charge sustaining modes of operation, the battery capacity is completely used first, and then the fuel is consumed. In the event that the car is operated until it runs out of gasoline, the gasoline-powered generator shuts down, and the Volt continues to operate, tapping into a reserve portion of the battery capacity which is below the regular minimum state-of-charge. The reserve battery capacity provides an extra 3 to 4 mi (4.8 to 6.4 km). If this reserve battery capacity is also exhausted, the Volt slows to a stop.[94]

2013/2014/2015 model year

As a result of its improved battery chemistry, the 2013 model year Volt increased its EPA's rated all-electric range to 38 miles (61 km) with an energy consumption of 35 kWh per 100 miles (788 kJ/km), down from 36 kWh (810 kJ/km) in the 2012 model. The total range with a full tank of gasoline and a fully charged battery is 380 miles (611.6 km).[76][78] The 2014 and 2015 Volt have the same EPA ratings.[4]

Europe

The Opel Ampera official all-electric range under the EU-approved UN ECE R101 standard for plug-in hybrids is 83 km (52 mi). Opel prefers to state that the Ampera's EV ranges is 40 to 80 kilometres (25 to 50 mi)[95] which is confirmed in tests carried out by ADAC Motorwelt.[96] The Vauxhall Ampera is reported to have a total range of 310 mi (500 km) .[97]

Fuel economy

United States
2012 Volt EPA/DOT Windows sticker showed potential fuel cost saving.

The U.S. Environmental Protection Agency (EPA) officially rated the 2011 model year Volt's combined city/highway fuel economy in all-electric mode at 93 miles per gallon gasoline equivalent (MPG-e) (2.5 L gasoline equivalent/100 km; 112 mpg-imp gasoline equivalent) and 94 MPG-e for the 2012 model year.[98] This rating considers a conversion factor of 33.7 kWh of electricity being the energy equivalent of a gallon of gasoline. The EPA rating in gasoline-only mode is 37 mpg-US (6.4 L/100 km; 44 mpg-imp). The overall combined city/highway gasoline-electricity fuel economy rating for the 2011 Volt is 60 mpg-US (3.9 L/100 km; 72 mpg-imp) equivalent (MPG-e),[92][99] The EPA also included in the 2011 Volt's fuel economy label a table showing fuel economy and electricity consumed for five different scenarios: 30, 45, 60 and 75 miles (121 km) driven between a full charge, and a never charge scenario. This information was included in order to make the consumers aware of the variability of the fuel economy outcome depending on miles driven between charges. Under the gasoline-only scenario (never charge), the 37 mpg-US (6.4 L/100 km; 44 mpg-imp) figure results from 35 mpg-US (6.7 L/100 km; 42 mpg-imp) city driving and 40 mpg-US (5.9 L/100 km; 48 mpg-imp) on the highway.[92]

For the 2012 model year, EPA revised the Volt's fuel economy ratings, increasing the combined city/highway rating in all-electric mode from 93 MPG-e to 94 MPG-e, and the highway rating was increased from 90 MPG-e to 93 MPG-e.[98] As a result of its improved battery pack, the 2013 model year EPA rating climbed to a combined city/highway fuel economy of 98 miles per gallon gasoline equivalent (2.4 L gasoline equivalent/100 km; 118 mpg-imp gasoline equivalent). The EPA rating in gasoline-only mode is the same 37 mpg-US (6.4 L/100 km; 44 mpg-imp) as the previous models.[76][78] The combined gasoline-electricity fuel economy rating of the 2013/2014 model year Volt is 62 mpg-US (3.8 L/100 km; 74 mpg-imp) equivalent, 63 MPG-e in city driving and 61 MPG-e in highway.[100]

The Volt digital panels keep track of energy usage by fuel source and average fuel economy.

When introduced in December 2010, the 2011 Volt was the most fuel efficient car sold in the American market in the compact class,[101] with a combined gasoline-electricity fuel economy of 60 mpg-US (3.9 L/100 km; 72 mpg-imp) equivalent (MPG-e),[92] until it was surpassed by the 2012 Ford Focus Electric in February 2012. The all-electric Focus has a combined fuel economy of 105 mpg-US (2.2 L/100 km; 126 mpg-imp) equivalent (MPG-e).[102][103] Nevertheless, the Volt remained as the most fuel efficient car with an internal combustion engine available in the United States until May 2014,[104] when the BMW i3 REx replaced the Volt as the most efficient EPA-certified current year vehicle with a gasoline engine, with a combined gasoline-electricity fuel economy of 88 mpg-US (2.7 L/100 km; 106 mpg-imp) equivalent (MPG-e).[100][105]

In December 2012 General Motors reported, based on data collected through its OnStar telematics system since Volt deliveries began, that Volt owners drive around 900 mi (1,400 km), or a month and a half, between fill-ups.[106] By mid June 2014, GM reported that among Volt owners who charge regularly, they typically drive more than 970 mi (1,560 km) between fill-ups and visit the gasoline station less than once a month.[107] In early October 2014, based on General Motors' real time tally of miles driven by Volt owners in North America, the company reported they have accumulated a total of 1 billion miles (1.6 billion km) traveled, of which, about 62.5% were driven in all-electric mode.[108]

The EPA's 2014 edition of the "Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends" estimated the utility factors for plug-in hybrids to represent the percentage of miles that will be driven using electricity by an average driver, in electric only or blended modes. The Volt has a utility factor of 66%, compared with 83% for the BMW i3 REx, 45% for the Ford Energi models, and 29% for the Toyota Prius PHV.[109] A 2014 analysis conducted by the Idaho National Laboratory using a sample of 21,600 all-electric cars and plug-in hybrids, found that Volt owners traveled on average 9,112 miles in all-electric mode (e-miles) per year, while Leaf owners traveled 9,697 e-miles per year, despite the Volt's shorter all-electric range, about half of the Leaf's.[110]

Europe

The Opel Ampera official equivalent fuel consumption under the EU-approved UN ECE R101 standard for plug-in hybrids is1.2 L/100 km (196.0 mpg-US; 235.4 mpg-imp) (83.3 km/L).[111] However, a leading Opel engineer prefers saying 169 Wh/km while battery-powered, and then 20 km/L petrol-powered. The ECE R101 standard weights charge-depleting mode as 76% and gasoline-only driving as 24%.[95]

Operating cost and payback period

According to Consumer Reports in December 2011, the Chevrolet Volt fuel cost in electric mode was 3.8¢/mile, while the Nissan Leaf had a cost of 3.5¢/mi. The Volt's higher cost per mile was attributed to its heavier weight. Their estimates used the U.S. national average electricity rate of 11¢/(kWh) and energy consumption rates as measured on their own, unofficial tests. When comparing the Volt in range-extended mode with the four most fuel efficient gasoline-powered cars as tested by the magazine, the plug-in hybrid had a cost of 12.5¢/mi (using premium gasoline) while the Toyota Prius had a cost of 8.6¢/mi., the Honda Civic Hybrid 9.5¢/mi., the Toyota Corolla 11.9¢/mi., and the Hyundai Elantra 13.1¢/mi. The analysis also found that, on trips up to 100 mi (160 km), the Volt was cheaper to drive than the other four cars because the Volt was able to drive 35 mi (56 km) using less expensive electric power. Consumer Reports found that, using their proprietary testing, the Volt overall fuel efficiency was 99 mpg-US (2.4 L/100 km; 119 mpg-imp) equivalent (MPG-e), and using only range-extended mode the overall fuel economy was 32 mpg-US (7.4 L/100 km; 38 mpg-imp) and equivalent to the Toyota Corolla. The report noted that, as of 2011, plug-in electric cars are more expensive to buy, and the previous operating costs do not include maintenance, depreciation or other costs.[112]

Chevrolet Volt (left) and Chevrolet Cruze Eco (right)

According to Edmunds.com, the price premium paid for the Volt in 2012, after discounting the US$7,500 U.S. federal tax credit, takes a long time for consumers to recover in fuel savings, often longer than the normal ownership time period. Edmunds compared the Volt (priced at US$31,712) with the same-size gasoline-powered Chevrolet Cruze (priced at US$19,656) and found that the payback period for the plug-in hybrid is 15 years for gasoline prices at US$3 per gallon, 12 years at US$4 per gallon, and drops to 9 years with gasoline prices at US$5 per gallon. At February 2012 prices, the break even period is 14 years. These estimates assume an average of 15,000 miles (24,000 km) annual driving and vehicle prices correspond to Edmunds.com's true market value estimates.[113]

In a similar comparison carried out by TrueCar in April 2012 for The New York Times, the analysis found that the payback period for the Volt takes 26.6 years versus a Chevrolet Cruze Eco, assuming it was regularly driven farther than its battery-only range allows, and with gasoline priced at US$3.85 per gallon. The analysis assumes an average of 15,000 miles (24,000 km) driven a year, a fuel economy of 34.3 mpg-US (6.86 L/100 km; 41.2 mpg-imp) for the Cruze Eco, priced at US$19,925, and a Volt price of US$31,767, after discounting the US$7,500 federal tax. TrueCar also found that with gasoline priced at US$5 per gallon, the payback time could drop to about 8 years if the Volt were to be operated exclusively on battery power. The newspaper also reported that according to the March 2012 Lundberg Survey, gasoline prices would need to reach US$12.50 a gallon for the Volt to break even, while the Nissan Leaf would be competitive with a similar gasoline-powered compact car at US$8.53 a gallon.[114][115]

Since the Edmunds and The New York Times pieces however, numerous rebuttal articles have surfaced that have identified various flaws in the methodologies and calculations used by Edmunds and TrueCar in their estimation of the Volt's pay-back period. Namely both sources strict use of the Volt's "gasoline engine only" EPA fuel economy rating of 37 mpg, when in fact when operated as intended any real-world use will most typically include an initial 38 miles of all-electric power during which zero gasoline would be consumed. Thus resulting in significantly higher total fuel economy that admittedly will be entirely dependent on how often and how far the car is driven. Many of these articles further suggest that the usage model used by TrueCar of 114 trips of 131 mi (211 km) per trip was not typical of the majority of American daily driving patterns, and their use of a projected cost US$3.85 per gallon as the cost of gasoline throughout the entire payback period quite unrealistic.[116] An article from the online automotive publication The Truth About Cars indicates that when the Volt is charged and driven daily exclusively on its available electric power for its EPA rated 38 miles of all-electric range (13,780 mi (22,180 km) annually) the payback period for the Volt would be much lower and similar to that of other plug-in electric-cars such as the Nissan Leaf or approximately 8.7 years (as indicated by TrueCar).[116]

Tailpipe emissions

While operating in all-electric mode the Volt produces no tailpipe emissions. However, the clean air benefit is mostly local because, depending on the source of the electricity used to recharge the batteries, air pollutant emissions are shifted to the location of the electricity generation plants.[117] The amount of carbon dioxide emitted depends on the emission intensity of the power source used to charge the vehicle. When the Volt's battery is depleted and the gasoline-powered engine engages, the plug-in emissions are similar to other internal combustion engine vehicles. The amount of total local emissions depends on how much the Volt is driven in all-electric mode and how much in charge-sustaining mode.[118]

United States

The California Air Resources Board (CARB) classified the Volt as Ultra Low Emission Vehicle (ULEV), as CARB tests do not account for the Volt electric range. With all tests conducted under conditions where the engine is running the CARB rated the Volt's carbon monoxide (CO) emissions at 1.3 g/mile (0.81 g/km), missing the limit for SULEV classification by 0.3 g/mile (0.19 g/km).[119]

The EPA rating for the model year 2011 Volt's tailpipe emissions is 84 grams of CO2 per mile, (52.5 CO2 g/km). Tailpipe emissions for the improved model year 2014/15 Volt fell to 81 grams of CO2 per mile, (50.6 CO2 g/km).[120] CO2 emissions are produced by the internal combustion engine in extended-range mode, and only after the Volt's primary battery charge has been depleted. In the other air pollutants category, the Volt rates six out of ten, with ten being best.[118]

The EPA also estimated the upstream CO2 emissions associated with the production and distribution of electricity required to charge the vehicle. Since electricity production in the United States varies significantly from region to region, the EPA considered three scenarios/ranges with the low end of the range corresponding to the California powerplant emissions factor, the middle of the range represented by the national average powerplant emissions factor, and the upper end of the range corresponding to the powerplant emissions factor for the Rockies.[109] The following table shows the Volt tailpipe emission plus total upstream CO2 emissions for the three scenarios, compared with other four popular plug-in hybrids and the average gasoline-powered car:

Comparison of tailpipe and upstream CO2 emissions(1) estimated by EPA
for popular MY 2014 plug-in hybrids available in the U.S. market as compared with the Chevrolet Vol[109]
Vehicle EPA rating
combined
EV/hybrid
(mpg-e)
Utility
factor(2)
(share EV
miles)
Tailpipe CO2
(g/mi)
Tailpipe + Total Upstream CO2
Low
(g/mi)
Avg
(g/mi)
High
(g/mi)
BMW i3 REx(3) 88 0.83 40 134 207 288
Chevrolet Volt 62 0.66 81 180 249 326
Cadillac ELR 54 0.65 91 206 286 377
Ford Fusion/C-Max Energi 51 0.45 129 219 269 326
Toyota Prius Plug-in Hybrid 58 0.29 133 195 221 249
Average MY 2014 gasoline car 24.2 0 367 400 400 400
Notes: (1) Based on 45% highway and 55% city driving. (2) The utility factor represents, on average, the percentage of miles that will be driven
using electricity (in electric only and blended modes) by an average driver. (3) The EPA classifies the i3 REx as a series plug-in hybrid[109]
Europe

The Ampera's official EU-approved UN ECE R101 carbon dioxide emission rating is 27g/km.[111]

Safety

Euro NCAP test results
Chevrolet Volt (2011)[121]
Test Points %
Overall: 5 /5 stars
Adult occupant: 30 85%
Child occupant: 38 78%
Pedestrian: 15 41%
Safety assist: 6 86%

The 2011 Chevrolet Volt standard features include 4-wheel anti-lock brakes with traction control; StabiliTrak electronic stability control system with brake assist; tire-pressure monitoring system; and 8 total airbags: dual-stage frontal, side-impact and knee for driver and front passenger, and roof-rail side-impact for front and rear outboard seating positions, with a passenger sensing system. There is also available an optional emergency assistance system.[1][89] A safety cage, built with high-strength and ultra high-strength steel, surrounds the passenger compartment to keep the space intact in the event of a crash. Crush zones framing the trunk and the engine crumple to absorb crash energy before it reaches occupants. Door hinges and latches in harmony with door structure and its steel reinforcements to keep doors closed during an impact.[122] The 2011 Chevrolet Volt was named "Top Safety Pick" by the Insurance Institute for Highway Safety. The Volt received the top ratings of "Good" for front, side, and rear impact crash tests, and also on rollover protection. All injury measurements except one were rated good, indicating a low risk of significant injuries in crashes according to the scale of severity employed in the IIHS’s testing. The Volt's lower rating of "Acceptable" was for torso injuries.[123]

The Volt received a five-star overall crash safety rating from the National Highway Traffic Safety Administration (NHTSA), the highest-possible score. This rating was obtained with NHTSA's New Car Assessment Program which is used for 2011 model year vehicles.[124]

Accident and rescue handling

In August 2010, General Motors began a training program for first responders when performing rescue duties involving the Chevrolet Volt. The program began at the 2010 Fire-Rescue International in Chicago, using a pre-production Volt for a live extrication exercise. Chicago firefighters demonstrated the sequence of tasks required to safely disable the vehicle’s powertrain and its 12-volt electrical system, which controls its high-voltage components, and then proceed to extricate injured occupants.[125] As of January 2011, additional training workshops had taken place in several other cities corresponding to the Volt's initial launch markets.[126] An Emergency Response Guide for the 2011 Volt was made available at its Service Technical College for use by emergency responders. The guide also describes methods of disabling the high voltage system and identifies cut zone information.[127]

GM recommends that a Volt battery fire be fought with water rather than dry chemicals, and rates the Volt battery as having no explosion or electrocution hazard as the result of a collision. The high-voltage system is designed to shut down automatically in the event of an airbag deployment, and to detect a loss of communication from an airbag control module. During the Volt development the lithium-ion battery pack was subjected to a wide range of tests, including overcharge, discharge, vibration, excessive heat and cold, short circuit, humidity, fire, crush, water immersion, salt water immersion, and nail penetration.[125]

Warning sounds

Due to significant noise reduction typical of vehicles traveling in all-electric mode at low speeds, the Volt is fitted with a manually activated electronic warning sound system called Pedestrian-Friendly Alert System for use when the car is operating at low speeds to alert pedestrians to the car's presence.[128]

Other features

Smartphone display for tank level and fuel range
Smartphone display of total and EV range
Connectivity

The Volt features OnStar Mobile application for owners to access vehicle information without being in or near the car. This smartphone application features the ability to check fuel efficiency as well as the vehicle's current electric range. It also helps monitor the charging, giving owners key information about the current charge level and the amount of time it will take until it is fully charged. The application also is able to control features such as locking/unlocking doors, and acts as a remote starter.[129] A five-year OnStar Directions and Connections service was bundled into the 2011 Volt's base price, which was reduced to three years for the 2012 model year.[130]

2011 model year

The 2011 Chevrolet Volt comes standard with cruise control; remote vehicle start-up system; 17-inch 5-spoke forged painted aluminum wheels; Bluetooth wireless technology for select phones; audio and navigation system with a center console capacitive touch panel and DVD and MP3 playback, with voice recognition; OnStar with five years of service; BOSE premium speaker system, with six speakers and sub-woofer; 30 GB hard drive for audio data storage; USB ports; three auxiliary, 12-volt, power outlets; power door locks and windows; power adjustable mirrors; programmable time of day charge control; and a 110-volt charge cord.[1]

Available options include; 17-inch 5-spoke forged polished-aluminum wheels; rearview camera system, parking assist package; leather-wrapped steering wheel; and heated leather front seats with selectable automatic activation.[1][131]

2012 model year

The 2012 Volt standard features include a remote keyless access with passive locking allowing the car to automatically lock and unlock with the key fob in close proximity of vehicle; OnStar turn-by-turn navigation for three years, and available in-dash navigation system; and Chevrolet MyLink including Bluetooth streaming audio for music and select phones. The 2012 Volt has seven option packages while the 2011 model had only three.[132][133]

2013 model year

The low-emission package standard available on later 2012 Volts destined for the California market is included in the 2013 Volts sold in New York state to allow their owners access to high-occupancy lanes. The liftgate and roof of the 2013 model is body-colored rather than black, and a new interior color "Pebble Beige" is available in both cloth upholstery and leather seats with suede inserts. A removable rear-seat center armrest is included in the premium trim package. Other changes include an improved audio system with GPS-based navigation; a comfort package that includes heated driver and front passenger cloth seats and leather-wrapped steering wheel; and there are a pair of available safety packages.[76][134]

2014 model year

Minor changes for the 2014 model year include a manual release for the charge port door in place of the electronically activated door found on previous models, and the addition of two new paint colors. A leather wrapped steering wheel becomes standard.[135]

Second generation (2015–)

The second generation Chevrolet Volt was officially unveiled at the January 2015 North American International Auto Show. Retail sales are scheduled to begin in the second half of 2015 as a 2016 model year.[13] The second generation Volt has an upgraded powertrain with a 1.5-liter engine that uses regular gasoline; the battery pack has new chemistry that stores 20% more electrical energy and uses fewer cells, 192 compared with 288 on the 2014 Volt; it uses a new power controller that is integrated with the motor housing; the electric motors weigh 100 lb (45 kg) less and use less amounts of rare earth metals. GM engineers explained that the second generation Volt was developed using extensive input from Volt owners.[136][137]

According to General Motors, these improvements allow the 2016 Volt to deliver an all-electric range of 50 mi (80 km), up from 38 mi (61 km) attained by the 2013/14 Volt. The gains in efficiency allow the second generation Volt to improve its combined fuel economy in gasoline-only (charge-sustaining) mode to 41 mpg-US (5.7 L/100 km; 49 mpg-imp), up from 37 mpg-US (6.4 L/100 km; 44 mpg-imp) for the previous model.[12][13] The 2016 Volt's combined city/highway fuel economy in all-electric mode is estimated by GM at 106 miles per gallon gasoline equivalent (MPG-e), up from 98 MPG-e for the 2015 first generation model.[138]

In April 2013, CEO Daniel Akerson announced that GM expects the second generation Volt to be priced on the order of US$7,000 to US$10,000 lower than the 2013 model year with the same features.[139] The 2016 Volt pricing will start at US$33,170 before any available government incentives, plus US$825 for destination. The starting price is US$1,175 lower than the 2015 Volt.[140] In California, order books for the second generation Volt were opened on May 28, 2015.[141]

In July 2014, Opel announced that due to the slowdown in sales, the Ampera will be discontinued after the launch of second generation Volt, and between 2014 and 2018, Opel plans to introduce in Europe a successor product in the electric vehicle segment.[142] In April 2015, General Motors confirmed that it will not build the second generation Volt in right-hand-drive configuration. Due to low sales, only 246 units had been sold in Australia by mid-April 2015, therefore the Holden Volt will be discontinued once the remaining stock is sold out.[143]

Production, price and sales

North America

Assembly of the Volt was assigned to Detroit/Hamtramck Assembly plant following the conclusion of the 2007 UAW-GM contract talks.[144] For initial production the gasoline engine is being imported from the Opel engine plant in Aspern, Austria.[145] In November 2010, General Motors began investing US$138.3 million at its engine operations plant in Flint, Michigan to support increased production of the Ecotec 1.4 L engine that is used in the Chevrolet Cruze, the upcoming 2012 Chevrolet Sonic, and the variant used in the Chevrolet Volt. The Flint plant was expected to start production of 400 engines a day in early 2011, ramp up daily production to 800 engines in late 2011, and to increase its capacity to 1,200 a day by late 2012.[146] In May 2011, General Motors decided to invest an additional US$84 million at the Flint plant to further increase 1.4 L engine production capacity.[147]

In 2010, General Motors planned an initial production for calendar year 2011 of 10,000 Volts and 45,000 units for 2012, up from the 30,000 units initially announced.[148] In May 2011, the carmaker again raised its production targets, as Volt and Ampera production capacity was increased to 16,000 units in 2011, including 3,500 units for exports and 2,500 demonstration units destined to U.S. dealerships, and the rest for U.S. sales. However, in November 2011 GM's sales chief announced that they would not meet its sales goal of 10,000 vehicles in 2011.[149]

Out of the 2012 production, General Motors expected to produce 10,000 Amperas for sale in Europe, 6,000 destined for Opel and 4,000 for Vauxhall in the UK. In addition, 2,000 Volts will be made available for the region.[150] By early 2012 GM abandoned its sales target to deliver 45,000 Volts in the U.S and instead announced that production in 2012 will depend on demand.[151][152] By March 2012 the Volt plant has a global production capacity of 60,000 vehicles per year.[152]