i just got this car, one of the things i liked about it was the dual zone...however, when i drive it the dual zone does not seem that dual. if i set it at 65on the drivers side, and the passenger side is set at 75 the vents seem to blow the same temp? when i reduced the passengers side to match, all of a suddent the 65 was blowing beautifully. anyone have any suggestions?

 

My '02 Envoy I had prior to my audi, was the same way, and had a backseat passenger climate zone too. It was good with the different climates, but does get weaker since it's working harder.
Haven't really tested this out in my A6

 

Mine does the same thing. The only car I have driven that has a perfect dual climate control was my Volvo 850. The driver could have full heat, and the passenger could have full cold and the fan would blow nice and hard out both sides. My A6 does a good job with maintaining dual zones with the A/C off, but once you turn it on, it seems to basically go to a single zone.