vibration in cerbera 4.2

[kajagoogoo]

Just back from a trip to Scotland giving the car its first long run. Every time I got to about 90mph, this incredible vibration kicked in. So much so that the view in the rear view mirror was completely blurred. Anyone experienced this before and knows what it might be?

[McNab]

Wheel balance, surely. If not, back to dealer for thorough check.