1976 Fiat X 1/9. I bought it in response to losing the purchase of a sweeeet MG midget during my college years. These things were notorious for vapor lock, and it had the mechanical fuel pump replaced with an electric one. Even then, it never quite ran right. I took it to college to have a sweet ride, but it ended up being a pain in the backside and cost me more than it was worth to try to keep it on the road.
The other nightmare vehicle was a 1988 Ford Bronco II. Bought it just to use as a 4WD utility vehicle, but the 1.9 liter engines were horrible for compression issues. Unbeknownst to me, the heads were cracked and got worse as I drove it. $1300 to replace them, and a year later, I had to replace the engine because the new heads from Jaspers in Indiana, did the same damn thing. There went another $1000 dropping in a used engine, and not three months later, the heads on the used engine did it too. Bottom line, was that I needed to drop a larger engine in that fat little Bronco II, but by that time, I had had enough. I junked it.