Im a mechanic so i hate some much more than others. -any BMW. Some of the dumbest most unnecessary problems on the market. The disa valve is located on the intake manifold. Its just a little plastic flap with a small pin in the center as the pivot point. The head of the pin points down. That way when the part fails the pin can fall out, go down into the cylinder or get caught in a valve and kill the engine. -Audi/VW. Sold as top of the line German cars. Most in the US are made in Mexico. Sure they are very comfortable but I would not recommended keeping past the warranty. If they aren't maintained meticulously they die prematurely. Especially if the timing belt isnt changed on time. I've seen more high mileage Datsun's than VW's. -Chevy S10 Blazers. I used to like them. But after owning one, replacing the engine and transmission, and being the only guy in the shop doing the tune ups on them I hate them. My wife has one and it seems like there is no escape after 10 years of not being in production. She wont fu king sell it. -My number one pick is mid 2000's F150s with the Triton 5.4 L V8. Dont get me wrong. They are actually great trucks. But the design of the spark plugs baffles me. If you do a tune up you are almost guaranteed to break one plug off in the engine. Google the spark plugs for a picture. Its not a normal plug. Because of the design the aluminum in the head around the plug oxidizes around the plug and locks it in place. So you try to remove it and half comes out and the half stays in the engine. In order to remove the remaining portion you have to buy a specialized tool kit which feels cheap and also tends to strip out. Went off the rails but those are my most hates cars. That killed 10 minutes. Back to being bored.