An energy conversion apparatus and method using recovered energy sources including motor vehicle kinetic energy (deceleration and shock) and wind resistance, supplemented by liquefied air transferred to the vehicle and by solar radiation thereto. The energy sources are combined, as available, to drive a compressor for supplying intake working fluid of a motor vehicle prime mover, wherein liquefied air provides pre-compression cooling of an atmospheric air portion of the working fluid. The liquefied air is made by recovered energy, stored and transferred between vehicles and between vehicles and stationary sites. In a hybrid version of the vehicle, exhaust heat from a combustion engine part of the prime mover increases working fluid temperature in a gas expander part, thereof; the engine and expander operating independently or together for improved vehicle propulsion efficiency.