Noticed vibration transmitted from presumably the driveshaft through to the centre armrest. Seems speed related esp on motorway and not engine related (no change in neutral). It's not really severe but definitely easily noticed. Anyone else noticed this?

I have a vibration that starts at just under 70MPH but I don't think it's from the center of the car, feels more like off side front.

Mine is periodic, ie, it build and fades over a one second period. It doesn't feel like an out of balance wheel but I could be wrong.

Off to the dealers next week.

I also have a vibration at around 75km\hr...the whole car vibrates [very slightly] and it is not felt through the steering so am assuming it is not wheel balancing.

I can only feel it sometimes on very smooth roads...

Could still be the wheel balancing, an out of balance rear wheel will not be felt through the steering wheel but will cause the kind of vibrations described.

I have found that any sort of build-up of crud on the wheel, inside the wheel, on the rims and so on can cause some scary vibrations, so as a first stop it might be an idea to pressure wash outside and inside the wheels, just in case.