I understand Volvo has a new AWD system these days but I have a 1998 V70 AWD that would have a vibration, not a huge vibration, but at the time a $36,000 car should not have. The dealer took everything apart, driveshafts, axles did them again all the way around and finally a new transmission. In the end they could not fix the car. My saving grace was the car was in the shop for the same issue that i called a lawyer who got me a decent settlement. My advice is to keep the car in the shop as long as possible, this helps your case if you decide you need to go the legal route. The good news is that Volvo is pretty fair when going this route. I kept our car because I wasn't able to swing a new purchase and it still has the vibration. Good luck and make sure the work orders document the issue in as much details as possible.