We bought this car 2 months ago (35K miles) and this vibration started a couple weeks later. It sounds almost like there is a bad tire in front - but they are new and show no signs of cupping.
It occurs only when you are cruising in 4th or 5th, or accelerating moderately. You can feel it through the accelerator pedal and floor/seat, but not through the stick. If you really punch it, the vibration is greatly diminished, but then mpg's go down (and tickets up).

If you push in on the clutch, it goes away (all rpms). If you let up on the accelerator, it goes away as well.

I have read that people have attributed something like this to a clutch, a friend thought it might be a throwout bearing, but the dealer assertained (after driving it around a bit) that it is in fact something wrong with the transmission and that we or a previous owner probably caused it, so the factory warranty will not cover it. I was drawn to this car because of the warranty - I did not expect this!

The dealer said that they would pull it out and disassemble it (at my expense) to see if it is in fact a manufacturing defect, but said if they found any sign of wear or a chipped tooth, I was looking at about a $6K job! Wouldn't any car show some signs of wear in 35K miles??

I have owned 3 manual trans Audis before and never, ever had a problem with a transmission. I'm having trouble with the concept of paying $6K on a under warranty car for a problem they are not completely sure what it is. Does anyone know what else it might be? I just cannot imagine that a manual transission can be falling apart in 35K miles.

 

That might be something really small, but also could be a problem with a tranny. sorry cant help u on this one, but 6k for the transmission repair is to high. I remember one guy on audizine could do 2.8 tranny (he finds one) swap for 1k.