Trying to narrow this down was a lot harder than I thought. It took many sleepless nights and days of work just pouring through my collection of Top Gear episodes to try and narrow it down. And finally I have come to a conclusion.
I have to give condolences to the amphibious car challenge (both of them) because they were so hugely funny and entertaining but I have decided to go with the outsider and choose the "Kit Car challenge" as my favorite. I loved watching all three of them trying to build a car together and seeing them bicker and curse each other. From James's filing to Jeremy's inpatients to get on with it (resulting in him have to install the same seats a few times), I was laughing all the way through it. But what made it that extra bit special was how it ended with the Stig getting pulled over by the Scottish police and taken away.
Classic Top Gear