After two months of
increases, the average fuel economy of all new vehicles sold in the United
States fell by a half mile per gallon last month, say researchers at the
University of Michigan Transportation Research Institute.
Average fuel economy of
cars, light trucks, minivans, and SUVs purchased in December 2011 was 22.2 mpg,
down from 22.7 mpg in November and 22.6 in October.
According to Michael Sivak,
research professor and head of UMTRI’s Human Factors Group, average fuel
economy of all new vehicles bought last month was down from 22.3 in December
2010, but up slightly from 22.0 in December 2009.
The all-time high of 23 mpg
occurred in March 2011. Average fuel economy for new vehicles sold is now up
about two miles per gallon from just four years ago.
In addition to average fuel
economy, Sivak and UMTRI colleague Brandon Schoettle issued their monthly
update of their national Eco-Driving Index, which estimates the average monthly
emissions generated by an individual U.S. driver. The EDI takes into
account both vehicle fuel economy and distance driven—the latter relying on
data that are published with a two-month lag.
During October 2011, the
EDI stood at 0.85, down from 0.87 in September and 0.86 in August. The index
currently shows that emissions of greenhouse gases per driver of newly purchased
vehicles are down 15% since October 2007.