I've noticed an unpleasant vibration has appeared on my 2008 TDV8 Vogue.
It's only obvious between around 55 to 85 mph (it isn't noticeable at all at 100+), and is felt most obviously through the seats. You can also see the sunvisors vibrating when they are down. I would say it's coming from somewhere rearwards of the engine, perhaps behind the driver. It's not felt at all via the steering wheel or pedals, there is no accompanying noise and it isn't noticeable under braking.
I've double-checked tyre pressures, tyres and wheel weights and there's no mud, snow or ice accumulated anywhere I can see. Calipers and discs also look fine, and it doesn't appear to be related to engine speed.
Any ideas? Do propshafts or driveshafts go out of balance?