In order to stimulate car sales, the government is offering cash incentives to spur car buyers to trade-in their old, gas guzzling clunkers for a new, fuel efficient car. On the surface, the Car Allowance Rebate System (CARS), also known as "Cash for Clunkers", seems like a great program. Simply take your clunker to a participating dealer and receive $3,500 or $4,500 trade in value toward the purchase of a new car.

Unfortunately what may appear to be a clunker to you may not qualify as a "clunker" for the CARS program. At first glance the rules seem pretty simple. Your trade-in vehicle must be in drivable condition. It must have been insured and registered to the same person for at least 1 full year and have been manufactured less than 25 years before the trade-in date. The clinker in the clunker program is the MPG requirement. The vehicle must have had a combined city/highway MPG (miles per gallon) rating of 18 or less when it was new.

Since my clunker may soon conk out, the idea of getting $4,500 trade-in value on an inexpensive new car was a big temptation. The strict MPG guidelines quickly brought that idea to a screeching halt.

Under the CARS guidelines, my 1991 Pontiac with 196,000 miles, a side window that doesn't work half the time, a broken air conditioning system and an unreliable heater isn't a clunker. Why? Only one reason, when it was new it had an MGP of 20.

While the CARS program may get people to the showroom to look at new cars, the MGP requirement will have many leaving the lot in their same, old car. If the CARS deal is the only thing that puts a new car within your reach, find out if your car qualifies for the program before you visit a dealership.

The FuelEconomy.gov website should be your first stop to find out your vehicle‘s MPG rating. After you select the model year and make of your vehicle, the combined city/highway MGP rating will appear in dark red under the heading "Estimated New EPA MPG" with the word "Combined" underneath. Ignore the individual city and highway ratings, it is the combined average of these numbers that is used to determine your eligibility for the CARS program.

If the MPG of your vehicle is 18 or less and you meet all of the other criteria, you will receive a $3,500 credit toward the purchase of a new car if the MPG of the new car is at least 5 miles per gallon more than your trade-in MPG. Purchase a car that gets at least 10 Miles per gallon more than your trade-in and your will receive a $4,500 credit.

Visit the official CARS website to learn all the details of the program.