Cadillac's latest concept car, the Converj is powered by an electric motor which draws its power from a battery charged both from the public grid and from an onboard internal combustion generator -- probably the same 1.0 litre four developed for the Chevrolet Volt. The engine is there solely to charge the power pack -- it plays no direct part in powering the car.

Integrated into the Converj's chassis, the 16 kWh, T-shaped battery pack's 220-plus lithium-ion cells give the car up to 64 km of generator-off -- read: emission-free -- driving. Recharging takes about eight hours from a 120V US power point, which translates to less than three hours on Australia's 240V grid.

The Voltec platform comes as close as anyone has yet to eliminating the range problems dogging pure plug-in systems. When it detects low battery power, the system switches on the flexible fuel generator to keep it topped up, giving the car an extended range of hundreds of kilometres -- until it runs out of fuel, like any normal internal combustion engine, and battery charge.

The electric drive delivers 370 Nm of instant torque, ensuring decent acceleration, and 120 kW of power. The top speed is 160 km/h.

"It's a logical extension of our plan to reinvent the automobile," says Bob Lutz (pictured riding in the Converj), GM's global product development vice chairman. "It clearly shows what a Cadillac electric vehicle could look like, and clearly indicates that global luxury customers can have a car that has both strong design and electric propulsion with a total range of hundreds of anxiety-free miles."

Read from this that the Converj is likely a production goer.