Evaluating the emissions and costs of light-duty vehicles

Light-duty vehicles and related supply chains contribute almost 25% to U.S. greenhouse gas emissions. Technological alternatives for fuels and powertrains have been proposed as a means to reduce the carbon intensity of... [ view full abstract ]

Light-duty vehicles and related supply chains contribute almost 25% to U.S. greenhouse gas emissions. Technological alternatives for fuels and powertrains have been proposed as a means to reduce the carbon intensity of light-duty vehicle travel. Most lifecycle assessment and fleet modelling studies that assess the lifecycle greenhouse gas emissions of these vehicles analyze representative or average vehicles operated under average conditions. Studies that have analyzed regional differences focus on emissions of electric vehicles and do not usually consider the impact of regional driving patterns on the fuel economy.

This study evaluates the lifecycle emissions and costs to the consumer of more than 500 light-duty vehicle models currently available on the U.S. market, subject to local differences in driving patterns, climate, fuel prices, and electricity mixes. To do so, we use a combination of models. First we consider a parametrized emissions and cost model. Next we couple this with a fuel economy model, a vehicle simulator, and local climate data, based on a model called TripEnergy.

We find that the emissions reduction potential of electric vehicles varies substantially across the country. When driven by someone living in a rural area with a cold climate, the electric Nissan Leaf emits about 21% less greenhouse gas emissions over its lifecycle than a Ford Focus. In urban areas with a mild to hot climate, this number increases to 44%. When factoring in differences in the electricity mix, such as between California and the Midwest, the bandwidth of emission reductions of a Nissan Leaf compared to a Ford Focus increases to between 0% and 75%. For larger vehicles, such as the Tesla Model S compared to a Mercedes-Benz E350, these bandwidths increase even further. We also find that the costs of operating an electric vehicle are considerably more stable to regional influences than those of internal combustion engine vehicles. Therefore, many of today’s electric vehicles are fully cost-competitive from the perspective of the consumer when considering similarly sized internal combustion engine vehicles in favorable areas, even without any subsidies.

We conclude that a focus on supporting electric vehicle adoption would be most effective at reducing emissions if focused on selected areas. These are areas where both the emissions and cost savings are most significant. Through an interactive tool, our research can inform consumers in those areas of both the cost and environmental benefits of driving electric vehicles.