OK spent about half an hour perusing the rallycross track at Silverstone today as the WEC sessions were going on.
Good news is it is going to be mostly dirt.
Bad news, there is a big US or Franciacorta style jump, and a very tight joker lap like Estering a real tight left and right.
Start line looks separate but I think as it is on the Stowe circuit, the circuit are trying really hard to not get any dirt on their moneymaking area which is the Stowe circuit where you attend training days experience days etc. (such a con as it is sold that you are supposed to be at Silverstone when in reality you are on a tiny track in the facility)
I can't yet work out where the transition is from the startline onto the dirt unless the track is anti clock, but if they are going anti clock then the jump is wrong as it is shallow entry side and steep the other, so it must be going the other way round.
I reckon seriously 70% on dirt, it is hard packed yellow sandy dirt, and at the moment the track is lined with piles of dirt and the mud they used to trench out the track, whether this stays I don't know, but I expect so as it lines the track and prevents the cars digging up grass and going onto the Stowe surface.
For those that know SIlverstone Stowe, the top hairpin looks like being used as the only tar part I can see, there is a transition before, then that tight right hairpin and then an immediate turn right onto dirt and into the jump, I think the start is alongside this where the pits are, (makes sense due to timing).
As I say, the bit I don't get is were the startline transitions onto the dirt, unless they are starting on dirt! Or they are starting behind the Stow hairpin.