January 2007

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DETROIT, MI - Call it the Mix-&-Match Principle of Automotive Architecture:

General Motors Corp. this month unveiled a new concept electric vehicle, the Chevrolet Volt, at the North American International Auto Show here Jan. 7-21 as the first embodiment of a new family of interchangeable power plants - including hydrogen fuel cells - and fuels powering a common electrical drive train, called the “E-Flex System,” with “E” standing for “electric” and “Flex” symbolizing flexibility.

Chevrolet’s new concept “Volt” passenger car, the first embodiment of General Motors’s new all-electric “E-Flex” drivetrain technology.

The common denominator in the small, short-overhang, four-seater similar in size to Chevrolet’s Cobalt is the replacement of the traditional mechanical drive train - a transmission, a drive shaft - with a common all-electric system. Power from the engine - a gas or diesel engine mated to a powerful battery and a plug-in system, or a fuel cell - is transmitted to the 120 kW (peak power, or about 160 hp) 320 Nm peak torque front-wheel electric motor by cable.

Top speed for the relatively light Volt would be around 120 mph-plus, with 100 mph continuous, and it would accelerate from zero to 60 mph in about 8.5 seconds, said Nick Zielinski, GM’s vehicle chief engineer who also rides herd on GM’s fuel cell “Sequel” and “Equinox” projects (H&FCL Oct. 06). At 3,140 lbs., the Volt weighs about the same as the 3,200 lbs. basic Cobalt. This includes a big lithium-ion battery, essential for energy storage, that is planned to weigh close to 400 lbs., extra weight that is largely offset by the absence of traditional powertrain components such as the transmission, and use of lightweight materials and technologies elsewhere in the car.

As described during a mid-December press briefing, the version shown in Detroit as a concept is a plug-in hybrid version that can be plugged into a conventional 110-Volt outlet for about six hours, giving a range of around 40 city miles on electricity alone. In effect, the Volt is an extension of and improvement on the rather controversial battery-powered EV1 that General Motors launched in 1996 and withdrew pretty quickly, to the chagrin of many enthusiastic lease customers.

An under-the-skin view of Chevrolet’s new concept “Volt” passenger car: this is the layout of the fuel cell version that GM says may be rolled out later this year at one of the upcoming 2007 auto shows.

When the battery is depleted, it would be recharged by a small, 1-liter three-cylinder 53 kW turbocharged engine running at constant speed - in effect, an “EV range extender,” as GM described it. The engine is “not sized to drive the car itself, only to charge the battery and the electrical system,” Zielinski added.

As presented in Detroit, the Volt’s i.c. engine is designed to run on E85, a blend of 15% gasoline and 85% ethanol providing a combined overall fuel economy of up to 150 miles/gallon, according to GM, with a projected range of 640 miles from a 12 gallon fuel tank in the rear.

There is still some uncertainty about the actual availability of a big lithium-ion battery. GM says development of such a battery storing 16 kWh and producing 136 kW peak is one breakthrough that hasn’t happened so far but that could be production-ready by 2010 or 2012. “The battery will be a critical item for future development,” said Zielinski. “Lithium-ion is the enabler in this configuration. It’s a substantially better technology than other battery technologies.”

GM hasn’t picked a supplier for the battery as yet. “We are in the process of selecting” an optimum design from a number of developers, said Jon Lauckner, GM’s vice president for global program management.

Other power plant options that GM is working on and that are likely to be shown at other auto shows even this year include small diesel engines that could run on bio-diesel, or fuel cells fueled by hydrogen. GM wouldn’t say where a fuel cell version might be shown, but it’s conceivable that it could pop up at either the Geneva or Frankfurt auto shows.

"We can tailor the propulsion to meet the specific needs and infrastructure of a given market,” said Larry Burns, GM’s vice president of research and development and strategic planning. “For example, somebody in Brazil might use 100-per cent ethanol to power an engine generator and battery. A customer in Shanghai might get hydrogen from the sun and create electricity in a fuel cell. Meanwhile, a customer in Sweden might use wood to create bio-diesel.”

The fuel cell variant mirrors the Sequel’s propulsion system, Burns added. “Instead of a big battery and a small engine generator used in the Volt, we would use a fuel cell propulsion system with a small battery to capture energy when the vehicle brakes. Because the Volt is so small and lightweight, we would need only about half the hydrogen storage as the Sequel to get 300 miles of range.”

The future fuel cell version would carry 4 kg of hydrogen in a 700 bar (10,000 psi) tank, Zielinski added.

Contact: GM Communications, Scott Fosgard, 248/857-0239, scott.fosgard@gm.com