This is our first BMW which we bought new with 4 miles on the odometer and its still going strong after 6 years and 135,000 miles. We average 500 miles per week on it back/forth to work. Highway gas mileage averages 26 mpg. My wife loves the car and I hope it lasts another 100K miles. We've had no engine problems, but regular maintenance is expensive. Our dealer had to repair the moon roof 3 times due to the guide rails - kept breaking. Fortunately those repairs were under warranty and we solved that problem by not using the moon roof anymore. The LED dash display burns out and is very expensive to replace - my mechanic tells me this is a known defect that BMW will not acknowledge.
The base i6 engine has plenty of power and gets you up to highway speeds quickly from the on ramps. Our 525 has the Sport package which makes it fun to drive on windy roads as the handling is great. The ride is excellent and gas mileage good.
Low and medium fan speed settings for the windshield defroster, the high only setting is loud and blasts your face/eyes. The slide out dashboard cup holders are worthless. HD radios are still an option today and should be standard in a BMW 5-series.