To examine the national fuel and emissions impacts from increasingly electrified light-duty transportation, we reconstructed the vehicle technology portfolios from two national vehicle studies. Using these vehicle portfolios, we normalized assumptions and examined sensitivity around the rates of electrified vehicle penetration, travel demand growth, and electricity decarbonization. We further examined the impact of substituting low-carbon advanced cellulosic biofuels in place of petroleum. Twenty-seven scenarios were benchmarked against a 50% petroleum-reduction target and an 80% GHG-reduction target. We found that with high rates of electrification (40% of miles traveled) the petroleum-reduction benchmark could be satisfied, even with high travel demand growth. The same highly electrified scenarios, however, could not satisfy 80% GHG-reduction targets, even assuming 80% decarbonized electricity and no growth in travel demand. Regardless of precise consumer vehicle preferences, emissions are a function of the total reliance on electricity versus liquid fuels and the corresponding greenhouse gas intensities of both. We found that at a relatively high rate of electrification (40% of miles and 26% by fuel), an 80% GHG reduction could only be achieved with significant quantities of low-carbon liquid fuel in cases with low or moderate travel demand growth.