[lightyear36]

Try sitting in a parked car on the street with all windows shut and no music - listen to the outside traffic's noise level. Actually a very acceptable isolation.

Now, try driving with a fully open driver's window. You'll notice a ghastly wind noise coming presumably from the mirror area at speeds above 50 mph.

Next, try folding the left mirror and drive with the open driver's window again. You'll notice a marginal decrease in the noise level.

Next stage would be to detach the left mirror completely and repeat the test. I'm not sure how to do this safely and correctly.

My point is: the noise isolation itself is fine and has been designed to withstand a certain noise level (otherwise at standstill you would hear the outside traffic as if it were inside the car). The problem is that something is causing an unproportionally higher noise level at higher speeds - either the outside mirrors or the chassis construction itself. In the first case there _might_ be a solution (one tip is to take a look at the mirror shape of the upcoming F80).