Concerns regarding global warming and energy security have increased the importance of decreasing emissions of CO2 from vehicles. Diesel vehicles have higher fuel economy and lower CO2 emissions than their gasoline counterparts. On a well‐to‐wheels per vehicle per km basis it has been estimated that diesel light‐duty vehicles in 2015 will emit 14–27% less CO2 than their gasoline counterparts. We estimate here that on a gCO2/kWh at peak torque, diesel medium‐duty vehicles currently have an approximately 10% CO2 advantage over their gasoline counterparts. At light and moderate loads the CO2 advantage for medium‐duty diesels with SCR after‐treatment will be greater than 10% (reflecting pumping losses when gasoline engines are operated at low and moderate loads). Emission of NO
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, HCs, and PM from diesel (and gasoline) vehicles has decreased substantially over the past decade and further reductions are anticipated in the future. In addition to the heavy‐duty segment, which diesels currently dominate, modern diesel engines are likely to continue to play an important role in the medium‐duty segment, and perhaps also in the light‐duty segment in a transition to more sustainable mobility.
