If you can't wait another year to buy a new car, do a little online research to find out about gas mileage and environmental impact.

Sticker shock therapy: Car mileage stats will soon be easier to compare.

UPDATE 5-27-11: As we reported a few months ago, the EPA and the Department of Transportation proposed revisions to the window stickers on new cars, with the goal of giving car shoppers more comprehensive information about a car's fuel economy and overall environmental impact. This week, the two agencies settled on the second of the two options pictured below. You'll see the new stickers on model year 2013 cars.









Here's what the new label will look like:

You can read about the label details on the EPA's car label explainer page.

Here's the backstory:

RODALE NEWS, EMMAUS, PA—Labor Day Weekend car sales seem to be an annual rite of passage from summer to the new model year. This year, as you browse the car lots holding your free hot dog and glass of lukewarm lemonade, the U.S. Environmental Protection Agency (EPA) wants you to know it's working to make car shopping a little easier. The agency is planning changes to those window stickers that tell you about vehicle gas mileage, and wants your input on how to make them more informative.

THE DETAILS: If you've ever been car shopping, you've seen the EPA's current window sticker, which provides pretty basic information about highway miles per gallon (mpg), city mpg, an average combined mpg, and the approximate cost of fuel per year. The agency is proposing, however, to make these labels much more comprehensive, by including not just gas mileage but also a car's greenhouse-gas emissions and levels of other smog-forming pollutants that come from its tailpipe. And the agency intends to present the information in such a way that makes gas-powered cars easy to compare to electric vehicles.

In its first of two proposed labels, the EPA would assign a car a letter grade, from A+ to D, based on its combined fuel economy and environmental impact. While the label would emphasize the letter grade, it would also tell shoppers a car's average highway, city, and combined mpg, and how that compares to other cars in its class, as well as to all other cars on the road. The label would also specify how many grams of carbon dioxide per mile and other pollutants come from the car's tailpipe, and how that compares to all other cars on the road (but not to similar cars in its class).

The second proposed label would present much of the same information, but would forgo the letter-grading system and, as with the current window stickers, place most of the emphasis on gas mileage. Labels on electric vehicles would provide the same basic information, but the EPA would convert a car's average electricity use into comparable mile-per-gallon numbers. Neither label would tell you how much pollution was emitted by power plants to charge an electric car.

Both proposed versions of the new labels would include individual bar codes, which would be able to be scanned by a smartphone, and would take you to a website where you can personalize your driving habit information and see how that car would perform in your day-to-day schedule.