Even though it caused me so much trouble, was a money sink and a bad decision, I would keep this forever if it was a hobby car.

Ford Sierra Cosworth.
It was tuned up with a T4 turbo and other mods to have 412bhp. Turbo lag was awful but when it kicked in it was the same sensation as a plane taking off, and with that turbo it sounded the same too. Whole care would shake if you floored it in 2nd, before you knew it you're at 130mph. Took it to 166mph a couple times on the motorway, felt like it was going to fall apart but fucking exhilarating.
Kept getting pulled over by police (looked like a drug dealer car and I was 19 - often with friends in car), car kept having issues - had to replace petrol tank, then fuel lines, then this then that. Sold it for a big loss and got a civic, stuck with Jap cars since. Tried to use a toy as an everyday car without the money to do it, but it was fucking fun and an adrenaline rush.