Top Gear is perhaps the only current BBC show that competes with Doctor Who in terms of worldwide popularity. What began as a motoring review show back in 1977 had a revamp in 2002, and is now watched by an audience of hundreds of countries, in dozens of languages. Yes it's had it's fair share of controversy, but for many it is just a simple way to sit back, relax, and veg out. Naming a corner on their test track after celebrated actor Michael Gambon is about the closest it gets to being high-brow, and for many viewers a particular highlight is the challenges that presenters Jeremy Clarkson, Richard Hammond and James May often face. Whether competing against one another to find the best car for a specific purpose, or working together to accomplish a set task, accompanied by Gerry Anderson music these challenges, also like Doctor Who, entertain audiences with thrilling drama, laugh out loud comedy, and are completely made up. Well maybe not completely, but they are hardly continuing the noble documentary tradition. Unlike the many 'reality' TV series that are somehow popular, at least those who make Top Gear have the decency to just go with it rather than trying to pretend otherwise. Take Jeremy Clarkson's test drive of a Reliant Robin around the streets of Sheffield for example: regardless of the fact BBC health and safety would not allow more than one uncontrolled topple before stopping the whole shoot, the uncanny 'coincidence' of Clarkson's repeated 'accidents' occurring just as various celebrities happen to be walking past should be enough to tip you off. As if this wasn't enough, Clarkson also announced he was unable to collect the show's International Emmy for Non-Scripted Entertainment because he was too busy writing a new script. In fact even the high court in London rejected a libel claim from car manufacturer Tesla, who were claiming misrepresentation, due to the show's entertainment rather than informative nature. Scripted or otherwise, any concern over the show's value for license fee money can be put to rest by the amount it generates in return, thanks to not just its international reruns (as well as just those on Dave), but also book, DVD, and Stig bubble bath sales. In celebration of the show's 20th (revamped) series being broadcast, here is the creme de la creme of the show's most hilarious and ambitious challenges...