Chevy Plug-in Volt Could Charge GM Hybrid Future

When the overall powertrain is considered, the concept PHEV has a 640-mile range and could achieve 150 mpg.

Scott Anderson

January 7, 2007

4 Min Read
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DETROIT – General Motors Corp. shakes up the global hybrid-electric vehicle contest with the Chevrolet Volt Concept, a plug-in HEV the auto maker says could achieve a startling 150 mpg (1.56 L/100 km).

To be revealed today at the North American International Auto Show here, the Volt signals GM’s overarching strategy to move from mechanical to electric-vehicle propulsion systems.

The concept is designed to run solely on charged electric power for a range of 40 miles (64 km). When that power supply starts to wane, a 1.0L, 3-cyl. turbocharged engine, burning gasoline or alternative fuels, kicks in to generate power to run the electric motor.

Unlike traditional HEVs, the Volt is a series hybrid because the internal combustion engine does not provide propulsion.

The car also is designed to store energy via a lithium-ion battery pack – supplier technology that is still very much in the development stage.

When the entire powertrain is considered, the Volt has a 640-mile (1,029 km) range.

“There are going to be people who don’t drive more than 40 or 50 miles (64-80 km) a day,” Bob Lutz, GM vice chairman-global product development, recently told Ward’s.

Chevy Volt PHEV concept aggressively styled.

“They will be perfectly happy with a plug-in hybrid,” he says. “They’ll be able to drive electrically a lot of the time and their fuel economy is going to be off the chart because they’ll almost never use fuel.”

Lutz and GM Chairman Rick Wagoner are scheduled to introduce the Volt today, but GM engineers say the concept car will not be left to collect dust after the show.

The Volt’s E-Flex platform is an adapted version of the future Global Compact Vehicle Architecture (Delta) that will underpin the next-generation Chevy Cobalt and HHR.

GM managers say they want to leverage the auto maker’s global manufacturing capability to manufacture the Volt in several different regions, rather than produce a low-volume niche model solely for the U.S.

The E-Flex architecture “strikes at the heart of some of the paradigms that govern this industry,” Jon Lauckner, GM vice president-global program management, says.

The Volt’s 12-gallon (45 L) tank can run on gasoline or plant-based alternative fuels, such as E85, a gasoline/ethanol blend.

“If it’s in Europe, it could be biodiesel; if it’s in Brazil, it could be E100 (100% ethanol),” Lauckner says. “GM is committed to making this a volume play globally.”

Engineers say annual home recharging of the Volt will consume about as much electricity as running three or four refrigerators a year.

Viewed another way, the price of electricity is the gasoline equivalent of $0.60 per gallon, assuming a $2 per gallon price and when driving the Volt 40 miles on electric power.

The per-mile cost for electrical power is roughly one third of the price of gasoline, GM estimates.

Nick Zielinski, chief engineer, says his team has conducted several months of simulations but has yet to roadtest the concept car.

A number of Volt engineers also worked on GM’s ill-fated EV1, a pure electric vehicle GM introduced in 1996 as a Saturn, but killed a few years later.

The auto maker has since been the subject of widespread criticism for the EV1’s demise, most notably with the summer documentary “Who Killed the Electric Car?”

Unlike the Volt, the EV1 did not contain an internal combustion engine.

Recharging the Volt’s battery from zero to full power is estimated to take up to 6.5 hours, compared with eight hours for the EV1, which had a range of just 90 miles (144 km).

The Volt’s electric-drive motor is capable of running on 161 hp (120 kW) of peak power from a still-to-be selected Li-Ion battery pack. The engine can churn out 236 lb.-ft. (320 Nm) of torque, while the onboard generator kicks out 71 hp (53 kW) of power, according to engineering plans.

The big uncertainty for the Volt remains the Li-Ion battery pack, and the limitations of the technology, which mainly powers consumer electronics.

GM recently announced two supplier contracts to develop Li-Ion batteries for the Saturn Vue Green Line PHEV, which GM has committed to building, possibly by 2010.

One battery contract is with Saft Advanced Power Solutions LLC, a joint venture between Johnson Controls Inc. and Saft; the other is with Michigan-based Cobasys, a JV between Chevron Technology Ventures LLC, a subsidiary of Chevron Corp., and Energy Conversion Devices Inc.

Li-Ion batteries are critical for future hydrogen fuel-cell vehicles, as well. GM is committed to building a production-ready hydrogen fuel-cell car by 2011.

Lutz suggest the Volt represents the missing vehicle link between gasoline engines of today and GM’s future hydrogen fuel-cell vehicles. “They’re enabled by basically the same vehicle architecture,” he says. “The question is, what do you use to generate electricity?”

It’s unclear if the production-ready Volt will retain its aggressive styling, which is somewhat reminiscent of the Chevy Camaro concept that was the star of the 2006 Detroit auto show. But program managers say the Volt is designed to make a statement.

“We wrapped – we hope – a very attractive package around it,” Tony Posawatz, vehicle line director, says.

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