Idler pulley seized at 198K, destroying the serpentine belt and stranding me about 75 miles from home. However, the repair was relatively inexpensive and quick.
Major coolant leaks at 200K, ended up replacing the valley pan, intake manifold gaskets, various coolant seals and the water pump (which was in good order, but not installed properly; turned out to be leaking).
Engine and transmission mounts at 201K; actually a pretty straightforward job. Also replaced the driveshaft flex disc and carrier bearing at the same time.
Clutch went out at 203K; expensive repair job, but worth it.
The rear shocks are worn out, brakes are just about done, the front end suspension components are in need of replacement, and I need to chase down a couple of minor oil and power steering leaks. After that, the car should be in great mechanical condition and ready for another 75-100K of service.
Well, the above comments about the maintenance would suggest that I'm severely disappointed with this vehicle. However, suggestions and assumptions about that are completely wrong. At this age and mileage, any car is going to need some serious work, and this car is rare enough to not be considered a disposable appliance.
BMW only made the E34 5-series with the M60 4.0-liter V8 and 6-speed manual transmission for one year: 1995. Also, only 3,202 of these cars were made worldwide. North America received about half of them. To put these numbers in perspective, about 12,000 E34 M5s were produced, making the 540i/6 a rarer car with less expensive maintenance costs, and performance levels nearly equal to its famous, hand-built brother.
Even with compromised suspension, the 540i/6 handles rather well, attacking corners with confidence. The 282HP four-liter V8 provides great power at any part of the rev range, and is perfectly complimented by the Getrag six-speed manual attached to it. Acceleration is very brisk and is still quite favorable by modern standards; put a good driver behind the wheel, and modern muscle car owners will be wondering how that old, boxy BMW is managing to keep up. Magazines rated the 540i/6 with doing the 0-60mph sprint in about 6.0 seconds; I'd say this would be an accurate assumption. A spirited passing maneuver, even on the freeway, will put you well beyond the speed limit quite quickly and effortlessly; watching the gauges is a must with this car, if you don't want to be paying fines left and right.
The power-adjustable sports seats (only available on this car and the M5 in the US) are somewhat stiff yet quite supportive, and cabin controls are ergonomic yet somewhat simple and dated compared to more modern cars. Front seat space is quite decent, while the rears are adequate; compared to more modern cars it is lacking. You can seat three adults back there, but they should be on friendly terms with one another. The trunk space is quite decent for both groceries and luggage for a road trip.
The E34's styling is timeless, and considered by many enthusiasts to be one of the last classic BMW designs. The sharp lines and aggressive stance give it a look unmatched by just about any modern car. The overall body style would be a good choice for someone who wants to drive something that stands out somewhat, but isn't flashy.
Maintenance costs aren't incredibly high when compared to other European sports sedans. However, higher-mileage cars will definitely need some work. I bought mine at a significant discount, and while some of these recent breakdowns have been very hard on the pocketbook, they are worth it considering the overall condition of the car. There aren't many cars that have an overall combination of performance, reliability (the only problem that actually stranded the car was the idler pulley), practicality, decent fuel mileage (16-18 city, 28-32 highway) and classic styling on the market, and fewer still that have a proper manual transmission.
Overall, owning an E34 540i/6 has been a blast, although sometimes frustrating.