Chevrolet Volt

Not a plug-in hybrid in the ordinary sense, and calling the engine a range extender undersells what it does. The Voltec drive has two motors and a planetary set, and above certain speeds the petrol engine can contribute mechanically to driving the wheels rather than only generating — so a driveability complaint cannot be reasoned about as though the engine and the wheels were unconnected. Sold as the Opel and Vauxhall Ampera in Europe. The engine running when the battery is not empty is usually normal rather than a fault: the car starts it to warm the cabin, to keep fuel from going stale, and to protect the engine in cold weather, and each of those has its own conditions worth checking before anything is diagnosed.