The Collaborative International Dictionary of English v.0.48:

Automixte system \Au`to*mixte" system\ (Mach.)
   A system (devised by Henri Pieper, a Belgian) of driving
   automobiles employing a gasoline engine and an auxiliary
   reversible dynamo. When there is an excess of power the
   dynamo is driven by the engine so as to charge a small
   storage battery; when there is a deficiency of power the
   dynamo reverses and acts as an auxiliary motor. Sometimes
   called Pieper system. -- Automixte car, etc.
   [Webster 1913 Suppl.]