Top Gear is a serious automotive journalist show - not for entertainment purposes. All their lap times are audited by a third party Accounting firm for accuracy. Not.
TG can post and show anything they want. It's a TV show - I wouldn't put their lap times in stone, as they can vary with the weather. Also, their competitions are staged (!) a bit - but it comes together very well. (The GT500 has a top speed of the Land Rover filming it!
)