I'd surprised if the demo cars have anything special done to them since they get cycled through and re-sold fairly quickly.I agree, I did a test drive recently on a RWD with 19s - they are much better in ride compared to my M3 on 18s and sound proofing. Not sure whether they have done anything to the test vehicle in terms of sound proofing - it was bit of Rangerovery (the evoques and Velar sound proofing) kind.