hi guys, just wanted to ask,
does your A6 have horrible wind buffeting
when u have your sunroof open?
it goes away when u open other windows with the sunroof
but when you just have the sunroof open, the noise is almost
unbearable. any suggestions on how to fix it?
anyone have similiar problems?

 

This is a problem that is typical of all modern cars that have aerodynamic designs. The wind tunnel testing is done with the sunroofs closed and opening them disturbs otherwise optimized, smooth air flow.

You've discovered the only real way to alleviate the problem -- open a window.

If it's any consolation, testing has shown that running the AC has just about the same effect on gas mileage as does opening the sunroof & windows. So, with that in mind, I open the sunroof & windows when I'm on backroads and the noise is less intense (ya gotta love the feel of the open road sometimes) and zip it up and go with the AC on the highway.

 

where have you heard that opening windows leads to the same MPG as using the AC?

im very interested in that statement

 

As you might expect, I can't give you any original sources. I've read it posted a few times (by people who's credibility I respect enough to quote them) on some other forums. Prompted by your query, I did a little searching online. The results are equivocal. The consensus appears to be that at lower speeds, you'll probably get better mileage by opening the windows. At highway speeds, there will probably not be much of a difference with AC probably winning out if you have a very aerodynamic vehicle (like the A6). Here's a link to Consumer Reports that has some thoughts on the topic: How to improve mileage

While the results are equivocal, my conclusion is this: At highway speeds, the greatest comfort (both temperature and noise) will be achieved with running the AC and recirculating the air so that you're not constantly cooling the hot outdoor air. On long trips, you may want to let some fresh air in periodically.

Of course, "your mileage may vary..."

 

Mileage doesnt really decrease that much with the ac on because it doesnt really take that much power to drive the ac compessor. Maybe a hp or 2. Opening the windows or sunroof creates drag which also requires more hp to maintain the same speed.

 

The sunroof switch has a detent in it, you've possibly felt it before and wondered why the switch sometimes gets stuck there; the position is less than fully opened and when left in that position the "helicopter" noise will not appear even with the windows fully closed.

 

Good call AudiSean -- I forgot to mention that one. If you have a hard time finding the detent, just open it all the way, and close it back a click or two. As AudiSean points out, you will significantly reduce the noise. The drumming will go away but you'll still get a bunch of wind noise.