The first article below discusses how back in 2010 the Obama administration passed a law requiring all stock production cars to obtain a fuel economy of 35.5 MPG or better.
http://www.washingtonpost.com/wp-dyn/content/article/2010/04/01/AR2010040101412.html
This article is an auto blog from last year with the latest in average fuel economy numbers for new cars at 24.9 MPG. Ten below the requirement with only three years left to achieve it.
http://www.autoblog.com/2013/09/12/average-new-car-fuel-economy-record-24-9-mpg/
We can get some sense of the overall impacts personal vehicles have on fossil fuel consumption and carbon emissions by looking at the average fuel efficiency and the number of vehicles on the road. This article suggests that movement of the world’s population towards megacities is causing some to believe that we will soon reach “Peak Car” whereby the growth of the number of vehicles on the road will stagnate:
http://www.bloomberg.com/news/2014-02-24/woes-of-megacity-driving-signals-dawn-of-peak-car-era.html