It's called 'Cash for Clunkers'. A bill that is in process of being passed in congress right now. You turn in your old car to the gov't and they pay you a certain amount of money towards a new car with better gas mileage.
Europe already passed this bill and it's been working like a charm, it's boosting the economy and getting cars with low fuel efficiency OFF the road and putting cars with better fuel efficiency ON the road. If you are interested in the details you can click the following links:
A good quote from the freep article:
'By next year, cars manufactured before 1999 will account for only 25% of the miles driven on U.S. highways but 75% of local pollution. That's according to Brookings Institution energy expert Jason Bordoff.'