Well first you should check your driving habit. If you drive aggressively like me your actual mileage per gallon will be much less than the advertised mileage. If your not driving aggressively and your still not getting the advertised gas mileage then you should get the car checked by a certified shop.The last thing you want to do in this economy is buy a car and then have to get nailed with payments for the next couple years. If you HAVE to get another car, consider getting a used car. A car that is even 1 or 2 years old with low mileage can be much much less than its new version