What is the Best first car?

I am 15 turning 16 soon and want a used car that is under 10,000$ used. My favorite car at the moment is the Mazda RX8 because I really like the motor, the looks, how it is manual, and how there are 4 doors but it looks like there is only two doors. But I hate the gas mileage..... I want a car I can work on, like exterior stuff and interior. Not really motor. Are there any good fast cars that have good gas mileage but are fast with four doors? Or at least four seats.