This paper describes the potential for the use of Dedicated EGR® (D-EGR®) in a gasoline powered medium truck engine. The project goal was to determine if it is possible to match the thermal efficiency of a medium-duty diesel engine in Class 4 to Class 7 truck operations. The project evaluated a range of parameters for a D-EGR engine, including displacement, operating speed range, boosting systems, and BMEP levels. The engine simulation was done in GT-POWER, guided by experimental experience with smaller size D-EGR engines.The resulting engine fuel consumption maps were applied to two vehicle models, which ran over a range of 8 duty cycles at 3 payloads. This allowed a thorough evaluation of how D-EGR and conventional gasoline engines compare in fuel consumption and thermal efficiency to a diesel. The project results show that D-EGR gasoline engines can compete with medium duty diesel engines in terms of both thermal efficiency and GHG emissions. Since gasoline has less energy per gallon than diesel, the D-EGR engine will have higher fuel consumption in gallons than the diesel, but the higher price of diesel fuel makes up for this difference in the US market.D-EGR also results in much lower in-cylinder and exhaust temperatures, which will help improve durability compared to a conventional gasoline engine. A D-EGR engine with its 3-way catalyst will be far cheaper than a diesel with DPF and SCR, so there is an opportunity for gasoline engines to regain medium truck market share.