The playing field is leveling fast. And as hybrid prices come down and gas prices go up, the extra money you’ll put in your pocket will only grow. How much can you save?

Well, for starters, before you even drive your new green car off the lot, Uncle Sam will give you a leg up by offering a federal income tax credit to new hybrid buyers. The size of the credit ranges from $650 to $3,400, depending on the vehicle. For a complete list, visit the Department of Energy’s site on fuel economy. Most states also offer their own incentives to go green.

But ultimately, it’s at the pump that you’ll really notice the difference. Unless you drive as much as a New York City cabbie (i.e. all the time), your annual savings at the pump won’t reach $5000, but $1000 is a safe bet for most.

Consider this: If you drive 15,000 miles-a-year and buy gas at $3-a-gallon, just a five-mpg difference adds up to $300. So, switching from that Town Car to an Altima will leave four times that in your pocket. As oil prices go up, so will your savings. Find out exactly how much you’ll save by using this mileage impact calculator.

Which hybrid to buy depends entirely on your needs, and there’s a growing array of options out there. Toyota’s (TM) Prius is still by far the best-selling hybrid (this year it became one of the top ten selling cars overall), but the Altima and Ford Escape are also popular choices.