In my case, what started as a small, defective, part blew up due to dealership mechanic incompetence.
I took my car in for an oil leak (1 year old). I was pretty sure, and the dealership confirmed, this was due to a leaking rear main seal. This was a known issue with a number of these cars so I did not worry too much about it.
The fix was to remove the front half of the car to get the engine and transmission out, then replace the seal.
When the engine/trans was removed, evidently one of the seals for the axle shafts was nicked so that seal needed to be replaced as well. Not a problem except there was a delay due to ordering of the wrong parts.
When I finally got the call my car was ready, I took time off work to go pick it up. The closest dealership was over 100 miles from my home. I got there just as the service department was closing, jumped in the car and took off. About a block down the road I noticed a horrendous banging noise underneath the car over bumps. To me it sounded like sway bar links for suspension. I called the dealership from the road and told them I would be right back. I got back and the service department had all gone home already.
So I left my car there and went home.
A couple days later the dealership delivered my car to me (loose suspension bolt).
After a couple of weeks I noticed a burning oil smell. I had let it go in case they had just got oily fingers on the exhaust. I looked under the car and found oil was leaking at a much higher rate than it had previously.
I ended up taking the car back to the dealership. Many parts were replaced over along with other parts such as the oil pan.
When I went to pick my car back up, I got a few miles and heard a sound like a dry bearing. To me it sounded like it was in the transmission. I pulled over, called the dealership and told them my wife would be bringing the car back to be fixed. My feeling was that they forgot to put oil back in the transmission (manual) after having it out.
My wife waited in the service department the next day for something like 6 hours, they finally came out and told her the transmission oil was low.
When I got the car home, I popped the hood to find many broken parts, lots of sensors with broken plugs and parts now being held together with zip ties.
The dealership had my car for almost 2 months for a repair that was supposed to take 2 days. A car less than one year old now looked like it had been worked on by a teenager with no clue.
Under AZ law, my car was eligible for lemon law protection so I went for it.