C5 Corvette.
No, seriously: I've only ever sat in one C5, at a car show. My Corvette experience was as follows: "Where's the handle? Ah, this door is quite lightweight. Interesting, it's so low..." *door latches* "DOORHANDLE! Where is it?" The feeling of sitting in that car was terrible, something I'd never felt before or since then. In the instant I spent inside that car -fumbling for that elusive handle- I spent months in a airport terminal, years in a waiting room. I was startled to learn that a feeling of boredom can be so bloody urgent.
The only time I'd felt anything like it was when I first crashed my car, oversteering my Altima off a hairpin. I felt no panic, no uncertainty. Just pure, distilled, guilt.
I don't care about the mechanical state of the thing, the car itself just repels, repulses me in such a primal way. I've personal experience with PTs and HHRs, I've been tortured by the Saturn Outlook's demented 6AT, humiliated by a bright yellow New Beetle with 'weiners' plastered across the window by an illiterate vandal, been made sick by a tilt-a-whirl overloaded Dodge Ram. But, for sheer dread, none of this is on the same level of that cursed C5 Corvette.