But those cars don't below to the BBC do they? They are part of that company that does the track days and remember - you loan a car to the BBC at your peril, if it gets smashed up they just hand it back so its not just a case of borrowing any car locally.
I am guessing it will depend on what cars they have in the studio that day. It will be more than likely done in a car they do a review on. During the morning the Stig will do 'his' time in it and then probably take someone out in it.