My 1991 Lumina - a car I love to hate.
I've been a very loyal GM customer for many years now, but my 1991 Lumina is the last one I'll buy. I've discovered reliable and high quality vehicles from Toyota, so it's "so long GM".
But, to the Lumina. Really, for the money, I've driven it a long way, but the aggravation has made it a painful experience. My white Lumina Euro 3.1L now has 300,000 km (180,000 miles) on it. Here's the weaknesses.
Brakes: very expensive repairs continually. Probably the most annoying thing. I've replaced everything in the braking system many times, sometimes exceeding a grand a pop. The brakes were undersized for the weight of the car, according to a GM engineer I met once.
Intake Manifold Gasket. This is a big gasket that sits on top of the engine and just underneath the intake manifold. This gasket on my 3.1L engine is known for premature failure, it breaks and the water pump will gladly fill the crankcase with coolant. The engine can be ruined. At first sign of this leaking (takes an expert to diagnose this), replace the gasket after going to the bank for a loan.
Heads: A known weakness, the heads crack and have to be replaced. Mine is oozing coolant a bit right now. A head replacement is a grand, and is risky according to my mechanic.
Electrical: The switches for the automatic door locks failed several times and I finally engineered my own switches using some from Radio Shack.
Struts: I cold weather the rear struts can freeze solid and when they do, the first bump can drive them through the top of the shock tower and into the truck. Which mine did.
What GM has to do is develop a good overhead valve engine and achieve some level of quality. Unfortunately, they can't get away with selling junk to the public for decades, and then get the public to believe that they've achieved something.