According to the reports I've seen (Consumer Reports statistics), the 328 is pretty damn reliable -- quite a bit better than average. The 335 is a bit better than average. The 335xi maybe a touch below average.
Hardly the crappy unreliable cars they're made out to be by some here.
Remember, few people post all over the forums about how trouble-free their cars have been.
For example, I never mention it, but my car has been flawless--9300 miles of perfect operation. No exploding sunroofs, no failing HPFPs, no electronic gremlims, no limp-modes, no nothing. I just find it boring to report "nothing wrong here."
Always do right. This will gratify some people and astonish the rest.