The car has an engine (1) driven air compressor (2) of positive displacement type. It has an air collector (14) charged in normal operation by the compressor, which supplies the collector via a valve (5) for the car braking across a heat exchanger (13).The stored air, on demand, flows through a valve (15) via a heat exchanger (18) and is heated. Then it is fed to the air compressor inlet side. The compressor delivers mechanical energy to the car engine such that the air expanded in the compressor is fed to the engine.
