I worked in dealers back in the 80's and did a short stint at the zone office for Pontiac, where we did overflow for other GM brands.
One person won a new Camaro from a radio station or something along those lines. Filled the tank with jet fuel and it made it to arbitration over that. I was real young at the time (20's) but had some decision type power. Shot it down and she took it to the next step up and GM paid to have basically everything that touches fuel replaced. I quit not long after that.
Another was a corvette. This is right after the year without vets and the new body style came out. One guy replaced his sparkplug wires, ran the wire across the main power wire to the digital dash, if you don't remember it was this dash:
This was a very expensive part. Guess that the wires the customer used are not the greatest in the world and the dealer decided that is what caused TWO dashes to blow before they figured it out. New don't really fault the dealer. Then the customer removed the plug wires and installed his own again and the dealer would not do it again. Came in again, this time "that smart ass kid" decision stuck. IIRC that dash was over a grand.....may not sound like much now, but in 1980's money.
Another guy drove his vet through a puddle and the engine started knocking. The dealer actually took pics of this. Before cell phones and all that, film in a camera that had to be developed, one rod looked like a J. There are leaves inside the intake, and around the fuel injectors (cross fire corvette) With the customer stating he drove through the puddle and the photos that one was also denied.