Boy, a lot of information and mis-information out there already. Don't listen to that dashboard-falling-out or Audi-saved-from-the-brink stuff. Audi's sales growth has been outpacing Mercedes and BMW since the late 80s. If you go to an airport or hotel parking lot in Europe today, you'll be flabbergasted how many Audis are sitting there compared to the other premium brands. They simply make better cars with innovation where it counts, i.e. in the drive train and in safety. And no, I don't work for Audi. :-) Anyway, back to your question. drawings_online probably got closest to what I would say. Not sure if I'd make the BMW the man's car and the Audi the one for the ladies. But it's true that the Z4 will require a more experienced and skilled right foot, especially if you live somewhere where you have to deal with water and/or snow on the road. But then again, the new TT can be very actively driven. In fact, in the standardized "track test" of a German car-TV-show, the TT quattro went around the rather twisty track in 19.42 seconds, followed by a Porsche 911 GT3 (!), an Audi RS4, and then the BMW Z4 3.0 at 19.6 seconds. In the end, I would pick the Audi. It's better to drive overall while being just as fast or even faster than the Z4.