Gearhart's paper examines the potential each strategy has to reduce vehicle energy intensity (EI) and carbon intensity (CI), investigating improvements that can be applied to traditional internal combustion engine (ICE) vehicles, as well as to advanced vehicles. Even with optimization of vehicle weight, aerodynamics, tire rolling resistance, transmissions, and idling and climate control loads, it was determined that ICE-based LDVs-including hybrids-could only meet GHG targets by replacing a large percentage of gasoline with low-GHG biofuels