I never kept a car long enough to let it get as bad as the ones mentioned here, the worst was my '85 Lebaron, some of the reason I took it off the road as that the floor was getting bad enough to be worried about my rather hefty self would fall through it, but it ran good much of the time I had it, and was frighteningly stable at 85+mph with the floor (and the whole body really) in such shape Probably the most dangerous car I have driven was the '86 Pontiac 6000 Dad used to own, the brakes were such that if you hit the brakes just hard enough to stop when it was slick (and sometimes when it was dry too), the thing would swap ends, wouldn't corner if it's life depended on it (wet or dry there too ), and It would also stall for the no apparent reason within the first couple miles after start up after having the fuel pump replaced. We were actually pretty happy when that car got totaled and Dad replaced it with our first XJ and my Lebaron, even at the end of it's life was a safer, more stable and more reliable car than that car ever was!