6: Hummer H3
The H3 is a compact SUV released at the end of the Hummer brand’s lifespan. It had a lot going for it, other than the fact that there was a recession going on. This meant consumers didn’t want Hummers anymore. Another problem with the H3 was that it used the five-cylinder Isuzu engine as the base engine (via Readers Digest).

This is one of the most faulty engines ever to enter a GM product. The engine is known for having an intermediate misfire that occurs from a defect in the air intake gaskets. This is not a cheap fix, and generally, once this happens, you’ll need a whole new engine.