OK, first off, I'm a BIG Top Gear fan, have been for years.
It is a VERY funny, well done show, I understand one of the VERY few left on the BBC. The main presenter, Jeremy, loves to take it to you Yanks, he really does seem to have a mild dislike for so many things American (but he bought a Ford GT40 when they came out).
Like I said, the show is very well done, but a LOT of it is staged, I have no doubt in my mind that that scene at the gas stand was staged, if not, it would have made the news, "BBC film crew attacked" as they have plenty of footage and the location etc.
Still, it is very entertaining.
Cheers!