That's because GM cars are crap. Japanese and European passenger cars are doing just fine.
I agree ... we tried them twice and both of them were crap.
Ford was OK and when things went wrong, they took care of them.
Dodge was the worst we had ... total piece of crap.
We drive Toyota usually and the quality is great but they are questionable when things go wrong.
They are like, "It's a Toyota, it's perfect!" ... POed me a couple of times.
Had a MB and a BMW ... both stayed in the shop all the time.
Got rid of both while under warranty.
Very irritating to have your car in the shop, even if you don't pay for the repairs.