There's a few that have bugged me over the years, like the blower speed control on my Yukon that gets condensation dripping on it and shorts out every so often, but most of my problems with GM are more to do with their marketing than engineering. When did you ever see a Pontiac advertised anywhere, and then they kill the brand from lack of sales. Same thing for the Camaro when it died in the 2000's, it was a great car with tons of potential (yes, it had the 90's plastics that everybody was fighting too), but not much in the way of updates and nothing for advertising, then cancelled from poor sales. Turbo buicks should have gotten much more press, but when they beat Corvettes, they were buried instead of celebrated (imagine if the Grand National team got to turbo the SBC in the 80's to fit in the C4? Or even take the GNX-spec 3.8 as an optional Vette engine?). Saturns were good cars for their market, but didn't get pushed very hard. The Volt is the best Extended Range EV that the world has never heard of. Imagine an EV that has a small battery you can use for a day's commute, then a small gas generator that lets you take it on the highway with Zero range anxiety. Perfect answer for most of the general car buying public, but no one knew what it was or how it worked. Those are the things that bug me most...
Furds and Chryslers all seem to take the stupid engineering cake for me though. A friend had a 90's Chrysler that would shut the radio off on right turns and kill then engine on left turns, even in parking lot speeds. Finally traced it to the main wire harness being attached to the steering linkage and flexing in the same spot for years, until wires started making/breaking contact every cycle. Ugh.
