I thought I would use the Vauxhall site to see how much the Z4 has depreciated in 12 months. You type in the registration and a value comes up.Has anyone used this before and are they very accurate? They didnt ask for extras and gave a middle of the road guide.I used this vauxhall site before when they used Glasses guide. That seemed much more accurate and fair to me. Be interested in your thoughts.Im still recovering from the shock of them suggesting I have lost £8000 in 12 months.