Speaking of Italian cars and gluttons for punishment, there is a guy around my 'hood that has a '70s Lancia Beta coupe and a '90s Alfa Romeo Milano sedan, both pretty worn out w/ faded paint....brave or maybe he's good at fixing Italian cars.
Not sure what the 'worst' vehicle is that I've ever owned, pretty much everything I've had has been pretty reliable and decent enough to drive. Only had 7 cars in 26 years..the '84 Ford Escort diesel and '86 Mustang LX 2.3 were pretty slow, the Bronco II a rust magnet and squirrely in cross winds. The '87 Mustang GT and '96 BMW M3 were a lot of fun, pretty reliable. My '00 Jeep Grand Cherokee has been reliable, though it's had a few expensive repairs as it's aged. The '11 Caddy STS has been great so far. I drove my sister's '84 Merc 500SEL for a while, it's quite a money pit for repairs but it has a lot of miles.