GM Plugs Back In with Hybrid Concept

17 Jan, 2007 By: Jeffrey Rowe

Promise of clean, profitable vehicle resurrected with the Chevrolet Volt

I saw many surprising things last week at the 2007 North American International Auto Show in Detroit. In what I considered an ironic twist, American manufacturers were touting their new vehicle offerings as clean, green and efficient, while foreign manufacturers were proudly showcasing much bigger vehicles and trumpeting the development of new V10 and V12 engines. This was a switch from previous years, although just about every manufacturer showed a hybrid of some type, whether gas/electric, plug-in, fuel cell or a combination thereof.

Volt Sparks Interest

The hybrid that caught my eye as one of the most potentially significant was the 2007 Chevrolet Volt concept vehicle. This is a bold attempt to resurrect General Motors' electric car after several years of failing to deliver on promises of high-tech concepts, as well as resisting tougher fuel economy rules. Then, of course, there's the birth and premature death of its famous (or infamous) electric car, the EV-1, that GM unceremoniously pulled off the road earlier this decade. This time around, GM seems optimistic that the Volt, or something like it, could sustain itself in the marketplace.

In the U.S., almost half the households travel less than 30 miles per day. The Chevrolet Volt concept vehicle is capable of 40 miles of pure electrical driving, which, according to the EPA, means that for most drivers in the city, the Chevrolet Volt will use little or no gasoline.
So, how else is it different?

The Chevrolet Volt is a five-door sedan constructed with a body-frame-integral structure with composite exterior panels and roof.

For starters, the Volt concept is a five-door sedan that uses electricity as its primary power source -- a 136kW lithium-ion battery pack. It is front-wheel drive and has no transmission, but does have a small (1-liter, 3-cylinder) turbocharged engine that runs on gasoline or E85. The engine powers a generator for charging the batteries, rather than turning the vehicle's wheels. GM claims that the Volt could travel approximately 640 miles on 12 gallons of fuel, yielding 53 mpg (miles per gallon), although the company also claims that most drivers would use the engine very sparingly for short trips, and others would get 150 mpg if the engine were used in regular intervals.

During operation, the Volt concept starts, runs and finishes in four basic steps or phases:

1. With the car fully charged, it draws power only from the battery pack.
2. After about 40 miles, when the batteries are down to an approximately 30% of full charge, the engine starts and runs the generator to recharge the batteries while the car is running.
3. The generator maintains the battery charge at 30% until the trip is completed, or until more fuel is added to the tank.
4. At the end of the trip, users plug the car into a 110V outlet to fully recharge the battery pack, which takes 6 to 6.5 hours.

The Chevrolet Volt concept takes advantage of ambient light that enters and illuminates the interior of the vehicle from the roof and beltline in the front and rear seats.

As part of the bigger picture, GM says it will introduce multiple propulsion systems that fit into a common chassis, using electric drive to help the world diversify energy sources and establish electricity from the grid as one of those sources. GM refers to this family of propulsion systems as the E-flex System. The Chevrolet Volt is the first variant of the E-flex System.

Larry Burns, GM vice-president of research and development and strategic planning said, "While mechanical propulsion will be with us for many decades to come, GM sees a market for various forms of electric vehicles, including fuel cells and electric vehicles using gas and diesel engines, to extend the range. With our new E-flex concept, we can produce electricity from gasoline, ethanol, bio-diesel or hydrogen."

The Volt concept sedan carries dimensions similar to a Chevrolet Cobalt, with an overall length of approximately 170", a height of 53" and a width of 71". However, the Volt's proportions, dictated by the layout of its electrically driven powertrain system, necessarily make it distinctly different from its mainstream Cobalt sibling.

Volt Design Elements

The Volt's roof, side glass and beltline are constructed of a transparent, glazed polycarbonate material that delivers the scratch resistance and gloss surface appearance of glass, combined with the formability of a plastic composite. As a result, the Volt provides the driver and occupants with exceptional visibility.

In addition to the upper daylight opening and roof, all exterior panels are composite, and each is designed as an attractive shape that could be displayed on its own as an art piece. As a result, the exterior panels fit together like a well-crafted puzzle, with flowing surface-to-surface cut lines that bring a sophisticated harmony to the Volt's exterior appearance.

The underside of the vehicle consists of a flat, composite molded belly pan that is integrated with the fascias and rockers for a clean, uncluttered and finished appearance. The belly pan -- which contributes significantly to the Volt's 0.30 coefficient of drag -- contributes to the sedan's overall impression of refinement and demonstrates that the design of the underbody was just as important as the upper body.

GE Plastics was a strategic partner in the design and development of the Volt, contributing the key materials technology to reduce part weight by as much as 50%. GE technologies showcased on the Chevy Volt include:

• Roof made with Lexan GLX resins and Exate coating technology,
• Rear deck lid and fixed side glazing made with Lexan GLX resins and Exatec coating technology,
• Doors and hood made with Xenoy iQ HPPC (High Performance ThermoPlastic Composites),
• Global energy absorber and hybrid rear energy absorbers with Xenoy iQ resins,
• Steering wheel and instrument panel with integrated air bag chute made with Lexan EXL resins,
• Front fenders made with Noryl GTX resins and
• Wire coating made with Flexible Noryl resins.

Volt's Future

What is the reality and probability of the Volt concept making it to production? GM admits that the Volt's future rests on battery technologies yet to be developed by outside suppliers. In fact, the Volt shown in Detroit was not actually drivable, but GM promises that will change by sometime this summer. Admittedly, a show car such as the Volt, for all of its promise, still has a long road ahead before it gets the green light for production. But, with the growing demand for all types of hybrids, the time might be right for GM to again introduce an electric car to the masses.

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