U-Mich Study
According to a monthly report by Michael Sivak and Brandon Schoettle from the University of Michigan, the average fuel economy of newly purchased vehicles in January rose after declining in December, but failed to reach a record high.

The average fuel economy (window-sticker value) of new vehicles sold in the U.S. in January was 24.9 mpg--up 0.1 mpg from the value in December, and up 4.8 mpg from the value in October 2007 (the first month of our monitoring). For a description of the calculations and the recent mpg values, please click here.

Emissions
The University of Michigan Eco-Driving Index (EDI)--an index that estimates the average monthly emissions of greenhouse gases generated by an individual U.S. driver--reached a record low of 0.79 in November 2013 (the lower the value the better). This value indicates that the average new-vehicle buyer produced 21% lower emissions in November 2013 than in October 2007. 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). Please click here for a brief description of what the EDI is, how it is calculated, and the current and recent values of the EDI.

According to GasBuddy, the national average in January was 4 cents per gallon higher than it was in December. Americans tend to buy less fuel efficient vehicles when gasoline prices are falling and vice versa when prices are rising. The average pump price in January according to GasBuddy was $3.29 per gallon, while prices in December averaged $3.25 per gallon.