The development of on-highway diesel engines is requiring more resources and technology to comply with ever-stricter emissions regulations. Increased airflow requirements of recently developed engines are not met exclusively with single-stage turbochargers. Two-stage systems have been widely used for off-highway high-horsepower engines and show potential use on smaller output engines.Although turbochargers are used as an exhaust gas energy recovery system, still a great portion of this energy is lost downstream the discharge pipe. The objective of this work is to provide a quantitative comparison of air handling system global efficiency taking into consideration the wasted exhaust gas energy. Experimental data from single-stage and serial two-stage turbocharged engines were compared with theoretical methodology.