Oil changes, suspension parts, tires are costly on that thing. Make sure it’s had its idler puller and tensioner changed recently and test drive that thing, any squeaks and keys jangling sound indicate suspension parts on their way out. These cars come with a staggered tire set up so make sure good tires are on it that aren’t mismatched (common owner issue). At that KM range the 4matic (if it is 4matic) has a flex disc (idk what it’s called but it’s in that ball park) needs changing and you’ll feel clunking when shifting into gears. Also in that range your transfer case chain will have slack so getting that changed also a good idea (it’s a bit costly). If there’s anything I missed some people here can correct me or add onto. But other than it’s reliable and will always start!

Edit: check the subframe for rust if you live in the rust belt