The Transportation Department and Environmental Protection Agency announced two new ones for 2012 vehicles. We've got a favorite. Sorry, gas guzzler. You fail — or at least, earn a D.One of two new EPA-proposed fuel economy stickers, slated to be rolled out next year and slapped on 2012 showroom cars, doesn't dip into the F-range. But it gives letter grades to autos ogled by prospective buyers, wh