DETROIT – General Motors Corp. is branding the electric-propulsion system powering its upcoming Chevrolet Volt extended-range electric vehicle, much the same way it has named previous internal-combustion engine families, such as Northstar and Vortec.

GM now calls the Volt’s drive system “Voltec,” as the auto maker reveals at the North American International Auto Show this week its intentions to expand its use to other divisions by unveiling the Cadillac Converj EV concept.

The Voltec system consists of a 16 kW lithium-ion battery, an electric-drive unit and a range-extending 4-cyl. gasoline engine that acts as a generator providing electricity to the drivetrain.

GM previously referred to the system as “E-Flex,” highlighting its flexibility in other concept cars at previous international auto shows by mating the electric-drive system to diesel engines and a hydrogen fuel cell.

At the unveiling of the Cadillac Converj electric-vehicle concept, GM Vice Chairman Bob Lutz tells reporters the auto maker might go with a larger battery for future applications outside of the Chevy Volt, or perhaps even a larger range-extending engine.

“But that won’t change the technology of the Voltec system,” he says.

“The important point to remember is that electricity drives the wheels at all times and at all speeds. When fully charged, the Converj can drive up to 40 miles (64 km) without using a single drop of fuel or without producing any tailpipe emissions.

“And it can also go several hundred additional miles once the small onboard engine spins to create more electricity.”

Lutz says GM also may choose to simply load the Voltec system’s battery differently with future applications to achieve an all-electric range of 40 miles.

With the existing Voltec system, the internal-combustion engine engages to generate electricity to power the vehicle and maintain the battery load after 50% of the battery is consumed.

“We could go up to 60%, 65% of use of the battery to get more performance or more range, because right now we’re only using 50%,” Lutz says. “Right now, no one else is being as conservative with the battery” as GM.

Lutz does not commit to whether the Converj will make it to production, but says the Volt remains on track to arrive in late 2010 as an ’11 model from the auto maker’s Hamtramck, MI, assembly plant.

GM announced last year it would produce the range-extending engine for the Volt in Flint, MI, and says at the Detroit auto show it will manufacture the vehicle’s battery pack at a yet-to-be-named site in Michigan with cells from South Korea’s LG Chem Ltd.