I've heard a lot of the same things in regards to the 330 e90 being pretty reliable and the 335's being a bit of hit and miss. However, I can definitely tell you an Audi is 10 times worse. A close friend of mine is a sales rep at Agincourt Autohaus and his cousin is one of the mechanics at another dealer and off the record they are having a hell of a time with the current and previous gen a4 and a6, so much so that it is not uncommon for a customer to bring the car in for warranty service 5 or 6 times, sometimes for the same problem. My mechanic which now owns a private garage but was the shop forman at Pfaff a number of years ago, echos the same sentiment, Audi is way down in reliability keeping mechanics busy, but not so good, especially from an inconvenience point of view and resale. Audi's resale sucks, which actually means you could pick a 2-3 year old one for less than an equivalent Bimmer then spend the difference on mechanics!
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