US power figures for this car were quite a bit lower than euro figures and the cars were a little heavier. The 2.5 litre unit was an M30 rather than an M20, most odd. The 525e was called the 528e in the US, it has a 2.8 engine designed for fuel efficiency. Many of the larger engined E28s have TRX alloy wheels. These use a special size of tyre which is difficult to get and very expensive.
Electric seats can fail, especially headrests.
The 1800 engine in this car can suffer badly from valve tick if badly adjusted. Ensure cam belts on the M20 engines are changed every 50,000 miles. M30 engines can suffer from oil starvation on the camshaft resulting in damage. This is preventable with a new design of hollow bolt for the oil feed bar. ZF HP 22 automatic transmissions can fail if revved strongly whilst in neutral or park.