Cadillac Vice President U.S. Marketing Don Butler (back) shows Environmental Protection Agency Administrator Lisa Jackson the interior of the 2013 Cadillac ATS compact luxury sports sedan Monday, January 9, 2012 at the North American International Auto Show in Detroit, Michigan. (Photo by Jeffrey Sauger for Cadillac)

Michigan Senator Debbie Stabenow gets behind the wheel of a 2013 Chevrolet Sonic RS performance vehicle after it was unveiled Monday, January 9, 2012 at the North American International Auto Show in Detroit, Michigan. The Sonic RS features a 138-horsepower (103 kW) Ecotec 1.4L turbo engine — the only vehicle in its segment to offer a turbocharged powertrain. The Sonic RS goes on sale in late 2012. (Photo by John F. Martin for Chevrolet)