I went from a Hyundai Getz 1.1 when I was 17 (great little car)>Mazda 626 2.0 GSI and now I drive a 260hp Volvo with sat nav/leather and im only 20!! Its all about picking the right car, you would be surprised what you can get, im not from a wealthy background or anything I just saved my money and bought the car for £2600 and the insurance cost me £780 (Aviva fully comp). Although where you live can severely change insurance prices!! Just make sure you have no accidents, convictions and stay on the insurers good side!!
Oh and another thing, don't get sucked in with these finance deals on new cars, they lock you in, and can get very expensive!!