My family has serviced several cars with Sun Mercedes of Mechanicsburg PA. They have been a very good service facility with a generous loaner program and a huge fleet of loaner cars. I have very rarely had to work around them not having a loaner available and the service has been almost perfect. We have also had them alert us to warranty work that we would not have known to have had done and in most cases of a problem, they have solved it quickly and without much grappling. In fact, I only have a few negative experiences, that all revolve around the service manager not wanting to cover damages to my car while in their care. (one being some obviously fresh gouges in my driver's seat that we guess was a tech sitting in the car with a screwdriver in his pocket. Service Manager refused to supply a replacement seat skin, even after his heat patch failed and the only way we resolved the issue was that I purchased a replacement skin and they installed it)
The service waiting area is comfortable, and the service desks are well set up.
On two occasions when I had left my car for service without getting a loaner, they had a service person drive it home to me and drop it off at my house. Steve has always let me know when there was something I could save money on, based on the work that we are doing, including when not to, and when it was a better time to change the timing belts so that it would cost less. This has only bothered me when I asked them to change all my glow plugs in my diesel and they said "well, only 2 needed replacement" I commissioned them to change them ALL and wanted them all replaced. I also asked them to clean out the system and the tech told me to just use a fuel system cleaner, and then because that didn't work out, my turbo was destroyed by coke building up in the exhaust and chunks being blown into the turbo. They did find a way to save me some money on the repair though.
At the end of the day, it has been a good and lasting relationship. I want to say that no one is perfect, but character is how you handle the missteps and failures. I can say that we have no outstanding problems and I will put off service in order to work with them instead of the other options I might have in the many cities that my business takes me to.