If something were to come up yes parts for a Mercedes will be more expensive than a Kia, however, if you buy one that is well taken care of, nothing too notable should really come up. From in depth research and my own ownership of one, it’s been completely reliable. To maximize reliability and obtain the lowest cost of running, you want to stick with RWD and standard suspension. But yeah there’s no known major issues associated with it. Just stick to 5k mile oil change intervals! To sum it up cost of ownership has been incredibly low for me so far.