I've had an E90 M3 for 6 years now, so I'm familiar(-ish) with that platform. Never owned an E60 but considering buying one in the next several months (assuming I can even find a RWD 6MT N52 car), so I'm trying to educate myself.

One thing I keep reading is that the E60 tends to be more complicated / less reliable / more prone to electrical issues than the E90. Is this true? If so, how?

Let's say I'm comparing a 2010 E60 528i and a 2010 E90 328i, as close to equal in spec as possible:

Both N52
Both 6MT
Both RWD

Is the E60 still more complicated? In what way(s)? Are there differences in electricals or construction, even in the same model year and similarly equipped?

Or does this "E60 is less reliable" idea mainly come from the fact that it's slightly older than the E90, had more standard equipment, and sometimes came with those finicky V8s?

 

Two things to check would be if the 3-series has “active stabilizers (dynamic drive)” and “active steering”… the first is not always present in E60s, but is a hydraulic oscillating motor on the front and rear stabilizing bars controlled by a module and I have no idea how it works other than it does something ridiculously complex and beneficial. The active steering was also an option on the E60s and it changes the ratio of the steering box – I think it just means sometimes the steering wheel has to turn less to do the same thing depending on what speed or other factors.

I have an E60 far above 200,000 miles and it has never had any problem. The age is obvious though on all the parts. Either way, it’s a good platform, even if expensive, but I don’t think there is a way to answer your question without going onto Autotrader and seeing which vehicle type generally has lasted longer while also factoring in how many were sold each year and cross-referencing the Carfax maintenance records. The reason I say there probably isn’t an answer is because maybe the 5-series is built better but also they may be more likely to fail because there might be so many additional modules and parts compared to the 3-series.

 

E90 has neither of those.

Active anti-roll bars resist body roll when needed and stay compliant the rest of the time for better comfort. Looks like they are "split" bars with a hydraulic actuator on each side to provide the twisting force, and the system takes input from steering angle and yaw sensors and pressure from the power steering pump (someone please correct me if I'm wrong). Simple concept I guess, but yeah – complex implementation.