[mof]

Well, as far as the open belt drive not being able to handle dirt...

Included is a pic of a 511 that had the body come partly off at quite a muddy race. I think there was starting to be a bit too mud much for it, though, there was around 400g of mud in the car after the heat

Here are the A finals (videos by AiR) so you can see the conditions for yourself (the 511 in the pic was in the B finals if I remember correctly, but the same conditions for them too)...