Cant believe I have never heard of this before today:
Yup pretty cool, I've been there as my sister used to live down the street in Woking/Surrey. Was a long time ago but as I recall was nice, lots of older and newer Benzes on static display. Not very big but was nice to see. They have the AMG on track experience as well which I did not do, but it looked like great fun though $$$$. There is also an aviation type museum if I recall with a full sized Concorde on display which you can go into and check out, pretty cool:
Mercedes World is quite something. Next to the old classic racing track Brooklands. The one with the banked track, the speeds those old cars reached were quite something and must have taken some courage. Lot going on at Mercedes World they have their own track and you can drive the current models round it yourself. Last time I was there though they had models of all cars in historical order. Not quite all as the 116 was missing. And I told them so. They had a formula one car that had been completely dismantled, every nut and bolt, and displayed as though it had exploded with everything in the right place suspended in the air.