The United States Congress is working on a "cash for clunkers" bill that offers vouchers to people turning in inefficient vehicles and purchasing ones of higher efficiency. Under the plan, passenger cars getting under 18mpg can be traded in for $3500 if the new vehicle is at least 4mpg higher than the old, or $4500 for a 10mpg improvement. New light duty trucks or SUVs get $3500 or $4500 if they were less than 18mpg and the new vehicle is 2 or 5mpg higher than the old, respectively. Large light duty trucks that get less than 15mpg are eligible for vouchers worth $3500 and $4500 if the new vehicle is 1 or 2mpg higher than the old, respectively. And finally, work trucks are worth $3500 if they were built before 2002 regardless of fuel economy because of the efficiency of the newer vehicles that even get the same mileage.