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Chevrolet Volt

The Chevrolet Volt is a plug-in series hybrid vehicle by General Motors, with production expected to begin in 2010. The company has avoided the use of the term "hybrid," preferring to call it an electric vehicle with a "range extender" ("extended range electric vehicle" or EREV), due to its design. This setup, however, is typically referred to as a series hybrid.

The vehicle is designed to run purely on electricity from on-board batteries for up to , or about half the range of GM's first electric car, the EV1 — a large enough distance to cover the daily commutes of 75% of Americans, which averages around . With the use of a small internal combustion engine driving a generator to resupply the batteries, the vehicle's range is potentially increased to on the highway (and which can be extended for very long trips by conventional refueling).

The Volt will qualify for $7,500 tax credit .

History

The Volt concept vehicle was officially unveiled at the North American International Auto Show (NAIAS) on January 7 2007 in Detroit, Michigan. An updated version was unveiled at the Shanghai Auto Show in April 2007 in Shanghai, China, and the final version was unofficially revealed on the internet on September 8, 2008. The production design was revealed at GM's Renaissance Center headquarters in Detroit on September 16, 2008.

The Chevy Volt will be built at the Detroit/Hamtramck Assembly in Detroit, Michigan.

Related and similar vehicles

The Opel Flextreme concept vehicle is based on the same platform and technology, but designed for the European market; it has a diesel engine and a hatchback body. Mazda is developing a vehicle similar to the Volt; Mazda tests are sufficiently advanced that Mazda has a working prototype in a Mazda 5 minivan body .

The 2003 Renault Kangoo Elect'road was the first modern electric vehicle with an on-board range extender. Although the History of plug-in hybrids shows many manufacturers have experimented with the technology, to date none have been mass produced.

Design

Concept vehicle

The concept vehicle had four doors with a rear liftgate, and it is capable of carrying four passengers. This is a significant change in design philosophy when compared to the General Motors’ EV1 of the 1990s, which only seated two. The top speed has also been increased on the Volt, from to . The battery pack size has also been reduced between the two, from about 300 L in volume in the EV1, to just 100 L in the Volt. The weight of the battery pack in the Volt will also be significantly less, primarily because the Volt will use lithium-ion batteries while the EV1 used heavier lead-acid and nickel metal hydride batteries.

Electromechanical design

GM executives report that battery technology will have a large impact in determining the success of the car.

To help spur battery research, GM selected two companies to provide advanced lithium-ion batterypacks: Compact Power, which uses manganese oxide based cells made by its parent company, LG Chemical, and Continental Automotive Systems, which uses nanophosphate based cylindrical cells made by A123Systems. However, on August 9, 2007, GM established a more close-knit relationship with A123Systems so that the two companies could co-develop a Volt-specific battery cell. This cell was later unveiled at the EVS23 industry convention in Anaheim, CA. Work with CPI has continued at a rapid pace, and in late 2007 CPI delivered two fully-functional prototype battery packs to GM's testing facilities. On January 31, 2008, A123 and Continental delivered their first prototype to GM's European test facilities. GM will likely use both suppliers for the Volt, although this remains a matter of speculation.

GM expects ten years of life out of the batteries. As of early 2008, they had started extensive battery testing and planned to have 10-year battery results in two years. Batteries were placed in Chevrolet Malibus for further real-world testing.

In February 2008, Andrew Farah, the car's chief engineer, said that design and production was ten weeks behind the original schedule, and that further slippage would mean that the 2010 deadline could not be met.

In April 2008, GM Vice Chairman Bob Lutz said that the first battery test mule was now running with a lithium battery pack.

In July 2008, GM confirmed that a non-turbocharged, 1.4 liter 4-cylinder engine will be used as the range extender, and that the intention is to build it in Flint Michigan.

In August 2008, Andrew Farah, the car's chief engineer, said that the 10 week delay mentioned in February had been "erased" as work on mechanical parts took place during that time. Farah further states the project remains on-track to hit the 2010 deadline saying "at this point, there’s nothing standing in our way of continuing to do what we said we’re going to do. In September, Bob Lutz indicated on an episode of the Colbert Report that they will offer an optional thermovoltaic solar power roof, allowing the owner to charge the battery by leaving the vehicle in sunlight.

GM unveiled production photos of the Chevrolet Volt along with its development team in September 2008.

Drivetrain

The 2007 Chevrolet Volt concept vehicle that appeared in the North American International Auto Show introduced the E-Flex drive system, which is an attempt to standardize many components of possible future electrically-propelled vehicles, and to allow multiple interchangeable electricity-generating systems. The initial design as envisioned in the Volt combines an electric motor and lithium-ion battery plug-in system with a small engine (1 liter) powered by gasoline linked to a generator. The vehicle is propelled by an electric motor with a peak output of . Ordinarily, the vehicle would be charged while at home overnight. A full charge reportedly takes 10 hours from a standard North American 120 V, 15 A household outlet.

Since the electrical drivetrain is not affected by the method used to charge its batteries, several options could be available for an engine. The newly released primary configuration specified by GM executives uses a naturally aspirated 1.4-liter engine with four cylinders. It is a heavier engine but is cheaper to produce than the previously announced turbocharged 1.0-liter three cylinder version. It would be a flex-fuel engine capable of running gasoline or E85 (85% ethanol, 15% gasoline). Fuel would be supplied from a "saddle" tank in size.

The second option is the Volt fuel cell vehicle, which appeared in the 2007 Shanghai Auto Show. Due to the high cost of fuel cells compared to newer lower-cost lithium batteries, General Motors has publicly suggested that the Volt will not be using fuel cells in any near term production vehicles. Other options have also been mentioned, such as a pure ethanol (E100) engine, and a diesel engine capable of running biodiesel fuel.

This general layout is considered a plug-in series hybrid design since mechanical power initially drives the generator, which in turn charges the battery pack. Power is then drained from the batteries to run the electrical motors which move the vehicle. The internal combustion engine does not have any mechanical linkage to the wheels (unlike current vehicles such as the Toyota Prius), and can run at a constant speed for both optimal efficiency and mechanical simplicity (there is no advantage in using a complex multi- or variable-cam or variable cylinder use design - these are typically used to increase efficiency and power over varying operating conditions).

GM plans to keep the lithium-ion battery in a state-of-charge (SOC) range of between 30% and 80%, with the on-board generator starting to recharge the battery at the 30% level.

GM has decided on a new descriptive terminology to distinguish it from traditional hybrids. They are calling the Volt an E-REV, for "extended-range electric vehicle. This is in part justified since there is no mechanical linkage between the petrol engine and the wheels. The design is conceptually similar to a modern electromotive locomotive, with a generator, an electric motor, and regenerative braking, with the addition of a storage battery.

Production and sales

In July 2007, General Motors stated that it would have the Volt on the U.S. market in 2010, and in early June 2008, they confirmed that production had been approved, with a target of getting the Volt into showrooms by the end of 2010. Following the conclusion of the 2007 UAW-GM contract talks, assembly of the Volt was assigned to Detroit/Hamtramck Assembly. Early estimates, from GM staff, were of initial annual production of 60,000 units, but these claims have been scaled back to a planned 10,000 units, as of May 2008, with a ramp up to 60,000 units in the second year.

At the British International Motor Show in July 2008, GM stated that they were considering building all of the Volts for the European market, branded Chevrolet, Opel and Vauxhall, at their Vauxhall plant in Ellesmere Port in the United Kingdom. In August 2008 GM stated that the Volt would be available for sale in Europe in 2011.

Price

As of August 2008, General Motors Chairman and Chief Executive Officer Rick Wagoner was quoted saying that the price of the Volt in the U.S. market would likely be in "the mid to high 30's" in the beginning the GM vice president wanted it at about US$30,000.

The indicated price for the UK market is GBP20,000.

Specifications

Fuel efficiency

For trips less than 40 miles, the Volt will not use any gas and so assigning a miles per gallon value would not be appropriate. The Volt is expected to get if the battery is discharged, or if fully charged every .

Battery capacity

The purely electric range of the Volt will be considerably smaller than that of the EV1, but the overall range will be much higher. However, there was a 1998 prototype version EV1 in series hybrid configuration, that also had four seats and the same all-electric range of as the Volt, featuring a combined range of , albeit with a different engine engagement control program and a turbine-based auxiliary charging system. In contrast to the current Volt, this car was actually a running prototype. The turbine could run on many fuels, from gasoline to compressed natural gas.

Controversies

EPA testing

As of September 2008, General Motors was reportedly in disagreement with the United States Environmental Protection Agency regarding how the Volt should be tested to determine its official fuel economy rating. The EPA reportedly wants the Volt to finish its test trials while retaining a full battery charge. General Motors has pointed out that testing the car in this manner will drop the Volt's estimated fuel economy rating to around 48 mpg since the internal-combustion engine would have to power the car during the EPA tests. If tested with the same EPA tests while being able to use the energy stored in the batteries the Volt would have a fuel economy rating of over 100 mpg. General Motors believes that the Volt is an entirely new type of vehicle and that the proposed EPA testing method would ignore the fact that the car can travel an estimated 40 miles on battery power alone before the engine has to start recharging the batteries.

In a response to the U.S. National Highway Traffic Safety Administration (NHTSA), GM indicated that "GM’s game-changing EREV technology should be treated as a low-volume application ... during the 2011-2015 timeframe.

Competition

GM faces competition from Nissan Motors, which announced their own electric cars on May 13, 2008, Toyota (with the Toyota Prius plug-in hybrid), Daimler’s Smarts (all-electric and Smart Forfour plug-in hybrid ), Mazda, Mitsubishi Motors, Tesla Motors Model S, Zenn, Think Global, and the Dodge EV, as well as a number of startup auto manufacturers .