I think it's the "average" MPG, but I'm not sure. I "think" that I can trade a truck in for a car since it meets the mileage improvement EASILY and get the credit. I put in the vehicle I wanted to trade in a calculator at Ford.com and they said it would be eligible for the $4500 credit. You can go to the ford website and put your vehicle information in and it can tell you if it's eligible or not. I'm not sure if we'll take advantage of it or not yet. We are wanting to sell our truck and our car....and we can get more in credit than the truck is worth with the cash for clunkers deal. But we have a Jeep my DH wants to keep and he'll be getting a company car so I'm not sure if it makes sense to buy a new car right now or not. We don't "need" it, but I'd love one with better gas mileage for every day driving than the Jeep. But does it make sense to take on a car payment for better gas mileage right now....HMMMMM that is the question