Had a clicking noise that seemed to come from underrneath the car so i started to remove the heat shields around the exhaust by the driveshaft center conection. Realized i didnt have everything i needed to get into this so i put it back together and one of the baffles seems to secure the middle of the driveshaft. Now when i drive it shakes from 30mph up did i throw it off balance? the holes seem to be just big enough to put it back the way i found it.

 

Played around a little more now it vibrates at 40mph goes away between 40-50 then when you slow down vibrates again till under 40mph.

 

I have same issue with 2004 XC90 and 100K miles. Started as occasionally clicking noise. Today full blown low freq rumble and harsh vibration. It occurs beginning at 35 mpg and smooths out around 50 mph. Not engine or transmission as it is worst when coasting from 50 mph down. Excessive vibration around 35 mph and worse coasting than accelerating.

 

Did you ever confirm what the rumble noise was with your 2010? I have an 08 doing the same thing around 40 mph.