No major problems. Rust on section below doors. (holes on passenger side)
Took it to two Pontiac Body shops where they told me it was not covered because they think it is due to stone chips! I've seen many, many cars much older than mine with no rust there, let alone holes. Now I'm stuck with a car that looks like its in excellent condition with rust holes in it! I can't believe I was not taken care of. And one of my back passenger doors won't open. Had to have truck latch repaired, also.
My previous car, a sunbird, had to have both doors replaced because of rust. It was covered, but very inconvenient! So I've had 2 Pontiacs with rust problems? Makes me wonder???
The reason you could have rust is because when it snows and the salt gets on it if you do not eventually wash it off it will eat through your metal. Mine with 72000 miles on it has not one spot of rust.
If you take of your car, it can last a long time. One way is to wash, especially in the winter, get the underbody sprayed to prevent corrosion. I have a 89 Caprice and the body has no rust!