As with most things, the more complicated it is, the more it costs to maintain.
A luxury european sports car will cost a great deal more to maintain than a Hyundai, etc....
If you're considering a used car that is out of warranty there is usually no reason at all to go to a dealer and lots of reasons not to go to a dealer.
A dealer has an incredibly high overhead and that is reflected in the cost of their parts and service.
Much better is to get a personal referral to an independent shop and have them do all the necessary work on your car.
The only exception to this would be if you are covered by a manufacturer's warranty and the cost will be paid by the manufacturer of your car.
Also, it's a good idea to stay away from any of the franchise type auto service places.
You'll get much better service and less hassles with an independent shop as well as save money.
If you want a car that was made in Mexico, buy the Lincoln. Be aware that OEM parts are more expensive for a Lincoln than a Cadillac.
I have a 2009 CTS and have had no problems . However , as these cars age , they will need parts like starters , alternators , plugs and wires . A Cadillac part will cost more than a Chevy part , but probably not much more than a Honda part. You don't have to service it at the dealer .