most unreliable: toss up between turbo rx7 and M3. bought m3 with 11k miles drove it until 150k miles jus about every thing broke.the rx7 i bought with 43k miles and it was a shitbox as well.

biggest pos was a 1979 chevrolet monza. It was infested with roaches. I think i bought it for 100 bucks and then sold it to another friend 4-5 months later. It was such a beater, but broke less than the two above. I also had an 81 fairmont that i drove for about a year. I covered the car in checkerboard penis stickers. the car got me through 1 riot( with 2 broken windows), and I think i broke another window trying to "door" a huge box on the side of the road that had a toilet in it(i didnt know about the toilet, when i smashed it).