I have recently bought a 2011 XC70 D5 AWD with 52000 miles on the clock. I have noticed at motorway speeds that the drive train is noisier than I expected and I can sense it working through the seat of my chair and accelerator pedal. It's not coming from a specific area like a bearing or rear diff issue but just a general increase in noise and slight vibration. Passengers don't notice anything but as driver I am aware of it and it spoils an otherwise lovely ride. To try and diagnose what is causing it I have carefully put the car in neutral whilst coasting and confirm it is not coming from the engine as engine revs do not effect it.

Also when coasting at a specific speed there is a small judder as the drive train takes up the slack when power is gently applied to keep the car at that speed. If a more substantial amount of power is added to accelerate there is no judder

Is what I am experiencing just the nature of the AWD system or do I have an issue which needs looking at?