The best cars with best gas mileage for teenagers are those that are small and inexpensive. While your son or daughter may want something as flashy as a Hummer, this is not a realistic first car for a teenager. Since many parents drain their budgets just to afford a car in the first place, the best way to invest your money is to buy a car that uses very little gas. Even a Smart Car is a good option for teenagers. When a teen is just learning to drive, you are likely limiting his or her time on the road. If you are only allowing your teen to drive to school and work, there is no need for a car with lots of cargo space. Small cars are easy on gas, and they are typically very affordable. It is easy to do comparison shopping on fuel-efficient cars. Simply look for the car within your price range that gets the most miles per gallon.