A '70 Ford Pinto. A real P.O.S. Everybody should drive a $50 beater for their first car. It makes you appreciate the better things to come.
Although, my best friend, a real go-getter even back then, bought a '66 TBird when he was 14 years old and drove it up and down his driveway until he turned 16. THAT is the best "First car" story I've yet heard. The guy eventually rigged his wiper washer to run inside the car and deliver a shot of whiskey. Ah, the good times we had in that car.