 Since the electrical drivetrain is not affected by the method used to charge the batteries, several options could be available for acting as an electrical power source.The primary configuration originally specified in the Volt promotional literature used a turbocharged 1.0-liter engine with three cylinders, a flex-fuel engine capable of running gasoline or E85 (85% ethanol, 15% gasoline), although this engine never made it to production vehicles.Other engine-driven power options mentioned were a pure ethanol (E100) engine, a diesel engine capable of running biodiesel fuel, or even a hydrogen fuel cell, once that technology becomes practical.