I had a '90 Buick Reatta that I bought in Indy and moved it to Fort Worth, TX. After time and out of warranty it would start poorly and run rough for a while and then smoothed out. Took it to James Young, a Buick dealer in Fort Worth. In short, they charged me $1330 for parts and labor over 4 visits and still hadn't fixed the problem. Then they replaced the coil pack and fixed everything. While they were at it they cracked the steering column plastic while checking the switch and turn signal. I complained to the Service Manager and I didn't have to pay for the coil pack and the repair and paint of the steering column, but I was still out $1330.
I bought a 98 Regal GS from them and at 36,713 miles, the left turn signal stopped working. The service advisor said it was just a bulb and proceeded to change them before signing it in. It did not fix the problem and he said it was some electrical part and would be expensive. I told him to please check if warranty would replace whatever was needed, but didn't expect it to. When I picked up the car they had replaced the turn signal switch assembly and there was no charge and he said the GM warranty picked it up.
While I'm typing, I had an 87 Ford Bronco XLT and the cruise control continually worked and didn't work. I had it to different dealers in Ohio and Indiana and they replaced different parts under warranty. Finally after the warranty expired I took it to an Indy dealer and he replaced some parts and I paid but on the way home, the cruise wouldn't work. I took it back and they replaced some more stuff and again I paid but this time, they fixed it. I talked to the service manager at the dealership and he gave me the Ford Regional office address and I wrote a long letter and told them the problem I had the since the truck was new. It took a while but they sent me a check for the work that was done after the warranty that I had paid for.
Just my experiences for what it's worth.
Karl