The use of fuel reformate from catalytic processes is known to have beneficial effects on the combustion process through enhanced dilution tolerance and decreased combustion duration, but the generation of reformate typically incurs a fuel consumption penalty. In this two-part investigation, efficient catalytic fuel reforming resulting in brake engine efficiency improvements is demonstrated. In part one of this investigation, the reforming energetics and catalyst performance was experimentally investigated over a range of reforming equivalence ratio and O2 concentration conditions in an effort to demonstrate the best conditions for efficient reforming. In part two of this investigation, the whole-engine strategy is investigated, combining the EGR loop reforming with dilution limit extension of the combustion process in the multi-cylinder engine. It is found that at the operating condition investigated, 2000 rpm and 4 bar BMEP, the reforming strategy employed in this investigation allows stable combustion with a volumetric equivalent of 45-55% EGR, whereas conventional EGR was limited to under 25% EGR for stable operation with stoichiometric engine exhaust. The raised the engine efficiency by a substantial amount and decreased the fuel consumption by more than 8% relative to the baseline operating condition. Thus, we demonstrate that efficient catalytic reforming to extend the dilution limit can lead to a substantial increase in brake efficiency in a multi-cylinder gasoline engine.