[RoundelM3]

^ Think whatever you like, but I have both a 335i and a 128i, and although I had the HPFP fix done on my 335i, that's the only problem I had, and it was quickly rectified. This is one poster's car, not every single N54-engined 135i, and it's not typical. But I can say that there is a HUGE difference in power between the N54 and N52 - the 128i is a nicely-balanced car with more than adequate power; the 135i is a high-performance car with a lot of tuning potential. As with any performance car, there is more complexity involved, and the OP's situation is not typical by any means - it sounds like more of a dealer problem than anything else. His car's "pedigree" isn't really known, as it was purchased from CarMax, and I've heard nothing but horror stories from friends and acquaintances who have bought performance cars from that organization.