The present invention, based on standard & readily available systems with minor modifications, is a readily implementable energy conserving system for automotive (HCV, LCV, passenger vehicles, cars), locomotive (bogies, wagons, freight cars, coaches) and passenger & goods lift applications to reduce pollution, increase efficiency, enhance mileage and reduce wear & tear of braking & power plant system. It is based on the accelerator position in case of automotive application and propulsion status in case of locomotives. It is independent of the brake in both the applications and is operational between deceleration commencing and acceleration resuming. It is applicable to fossil fuel, electric & hybrid transport drives. The process can use pneumatic, hydraulic or electric as energy transfer medium or a permutation & combination of the various media and is detailed herein for the pneumatic variant. Additionally, the process based on the pneumatic variant and a Dual Use Vane System that operates as a compressor and motor as detailed herein, is the best configuration. It has the lowest Life Cycle Cost, lowest emission of the system materials on Cradle-To-Grave basis and highest specific energy vis-a-vis existing art.