Rich Hall (who has been here a lot) was in a QI a while ago when quite a long conversation ensued - he chimed in at then end - "I have not understood a word that has been said for the last 5 minutes". ...Some of us Yanks do understand Britspeak, y'know.
Seriously, though; excellent post, Yickle.
I think you forgot to recognise the fact that in the earlier days of TGUK, they were the only car show with the format we are familiar with now. Back then they did not have any other show to compare themselves with. They were the pioneers of creating entertaining car shows. Also notice how much more entertaining Top Gear is when they moved away from "statistics-based" car reviews to more "emotion-oriented" car reviews. Car reviews can be done in under 5 minutes: you just rattle out how big is the boot space, fuel economy etc which frankly is boring to non-technical car fans.Once in a while I would play the earlier seasons of the new TGUK in the background on my computer at work. Truthfully the casts in early seasons of TGUK weren't that great. Even JC himself was not as funny or as smooth as he is now. He would have hiccups during a speech and that sort of thing back in the days. He certainly wasn't that funny back then either. Both the script writers and the actors of TGUK have improved drastically over the past 8 years. Top Gear back in the days was not as entertaining as it is now. It is very typical of any long running TV show.
The chemistry of TGA casts will improve over time. This is only their first season. People rate them with a longer yard stick only because TGUK is that good. Many people seem to forget the fact that TGUK didn't start out perfect either.