If the efficiency results reported in references, discussed in
Introduction, are combined with the present experimental results, it is safe to say that the brake thermal efficiency of a hydrogen engine exceeds that of a gasoline engine over the entire speed and load range. The present results quantify this efficiency increase.
NOx emissions control incurs an efficiency penalty at the
higher loads, although hydrogen keeps its efficiency advan-
tage over gasoline. At low loads, important in drive cycles as well as for everyday driving, the efficiency gains of hydrogen compared to gasoline are particularly high (up to 60% relative increase of the BTE). If this is the case for a gasoline engine that was converted to allow operation on hydrogen, with a result- ing compromise for the BTE on hydrogen, one can expect the
differences in BTE to be even higher for a dedicated H2ICE.