The pneumatic hybridization of power trains is especially effective when it is combined with stnmg downsizing and supercharging of spark ignited engines. This paper presents measurement results obtained from such an engine. Specifically, performance measurements for all additional engine modes are shown. The pneumatic motor mode and the pneumatic pump mode are individually optimized over their whole operating range for maximum recuperation efficiency. Jointly with the conventional combustion mode and the pneumatic supercharged mode, they are implemented in one engine control svstem, thereby enabling the switching between all modes. A dynamometer simulates the longitudinal dynamics of two series production vehicles for the modifled engine. This experimental setup, defltied as emulation, is used to accurately measure the engine's fuel ccmsumption in the MVEG-95 and federal test procedure (FTP) drive cycles. Causal and noncausal energy management strategies are presented and used for choosing the engine mode during a drive cycle. Fuel savings of up to 35% are measured when comparing the modifled engine to the vehicles' statidard engines with the same rated power. Hybrid pneumatic vehicles (HPVs) may prove to be a viable alternative to hybrid electric vehicles since fuel savings and driveability are cotnparable, while the added cost is expected to be substantially lower for HPVs.