Nice, I'll check out some reviews. Do you have any experience with it?

 

Also, do multiple layers further increase effectiveness? If so, is it worth doing?

 

Layering works, also ive used it its good product just we have goten some really hot days and cold days temperature changes do play with it a bit. The trunk you have to wash it off make it dryy if possible sand off the gloss coat to make it stick better. 2 layers does the trick 3 at the most.

 

Hellz yeah, thank you!

 

I've sprayed the wheel wells of past cars with rubberized undercoating to muffle wheel/tire noise while driving, and it's been a noticeable difference. To be fair, they were inferior cars to the A4, so the A4 may not benefit as much from doing it, but I doubt it'll hurt. Be careful if you do it though - don't bury any sensors or body bolts with undercoating. You'll regret it later if you need to remove them.

 

Thanks, I'll try that.