In 1900 a Belgian carmaker, Henri Pieper, introduced a 3-1/2 horsepower "voiturette" in which the small gasoline engine was mated to an electric motor under the seat. When the car was "cruising," its electric motor was in effect a generator, recharging the batteries. But when the car was climbing a grade, the electric motor, mounted coaxially with the gas engine, gave it a boost.
The Pieper patents were used by a Belgium firm, Auto-Mixte, to build commercial vehicles from 1906 to 1912.
E. and H. Hora made some under licence in the UK.