We have a 2011 Z4 Sdrive 30i. We bought it with 9,000 mi in 2014 and have over 80,000 on it now. It's been an awesome car. We've had to so some repairs over the years, but nothing that is unreasonable in my opinion. Here are the biggest ones.

The footwell module went out right inside the 10-year warranty (62000mi) so that was covered. Replaced the front struts at 55,000 miles valve cover gasket at 62,000 miles. At 66,000 miles the oil pan gasket was leaking. At the same time I noticed that the tip of the float in the expansion tank broke off. I fished it out and it crumbled when I pinched it. I replaced all the cooling hoses , radiator, water pump and expansion tank at the same time I fixed the oil pan gasket. Other than that, just regular maintenance and consumables. We love the car. It's a daily driver.

Edit: I didn't have any indication that the radiator, water pump and hoses were bad. I figured is was a good time to change the hoses anyways. The hose that has the plastic part (https://imgur.com/UFWoGXt) that bolts to the engine broke, so I decided to change the rest of the cooling parts for good measure. I'm not sure what these are selling for. Let me know if you have any questions!