I actually have and had this problem for a while, it is very complicated...whirring noise at 20mph....my car is S40 T5 2004.5 now has 48000mi...and nothing but problems in this matter. It seems the dealership is giving me the run around...replaced rotors, then bearings, then brakes all in a row when each didn't fix the problem, then the dealership says it must be a tire problem and ended up replacing them with the same tires that I bought the car with at 25K mi splitting the cost, $500, I could still hear the noise as I drive a lot, and when I left, I still heard it, dealership insisted they couldn't, and I had no choice to leave and come back when it was apparant. It took several trips and now it is in the shop again and they are saying it is the tires, need to be replaced, with a different brand from what they replaced with, if that makes sense, and it'll only cost me another $600, they say they are splitting the cost again. So basically I have had 2 new sets of tires on a 2 year old car with a third to be done at 48K. I don't know what to think. I contacted Volvo and they are researching this but I don't think much can be done. Something is wrong with this car and although I love it, I am gettting rid of it. Volvo isn't much support right now as well, when I discussed what was done in the past, all warranty work, they did admit it was an awful lot of replacing. Does anyone else have similar problems or any idea what I can do?