In this work, a new air hybrid engine configuration is introduced in which cam-based valvetrain along with three-way and unidirectional valves make the implementation of different air hybrid engine operational modes possible. This configuration simplifies the air hybrid engine valvetrain significantly and relaxes the necessity of using fully flexible valvetrain in air hybrid engines. Utilizing the proposed configuration allows compression braking (CB), air motor (AM), startup and conventional modes of operation to be realized. The proposed configuration is modeled in GT-Power and the deceleration of a typical vehicle, utilizing only regenerative braking system, is simulated. The efficiency of the system in storing the vehicle's kinetic energy is determined using second law definition for efficiency. The stored energy can be used to either start up the engine or run the off-engine accessories. These two modes are studied and compared.