A technical analysis of model year 2011 US automobile efficiency

This paper investigates the new 2011 automobile fleet to quantify the variation in models’ efficiency and underlying technology attributes. This involves analysis of test data to quantify the aerodynamic, rolling resistance, and powertrain efficiency characteristics of each model, as well as analysis to understand relationships between these and vehicle fuel consumption. The findings indicate that while vehicles are about 14% efficient on average, there is wide variation and direct evidence of dramatically improved powertrain efficiency within existing models. Existing gasoline and diesel models demonstrate improved powertrain efficiency by over 25%, hybrid gasoline-electric powertrains by over 50%, fuel cells by a factor of three, and all-electric by a factor of four as compared to the average 2011 vehicle. Advanced aerodynamic and tire rolling resistance technologies are also in evidence.

► New 2011 US automobiles are 14% efficient on average.
► Direct evidence of 25%+ improvements with internal combustion, 50%+ from hybrids.
► Electric and fuel cell vehicles offer factor of 3–5 efficiency gain.
► Larger vehicle engines capable of same powertrain efficiency as small cars.