Yeah, I've been told about this episode of Top Gear before, but I hadn't seen it till just this evening (thanks for the loan, Paul!) Top Gear's terrific: I'm not even a car person and I love this show. They're hilarious. And they do shit like this ... because they can. This clip, if you have ten minutes, is worth watching.
London Calling: the Top Gear guys race across London by car, transit, bike, and boat.
This is an abbreviated version of the race from the show (it misses a lot of the phone calls back and forth, and the others' slightly gleeful speculation of whether Hammond, on the bike, is still alive), but still really entertaining. Even if it's just to listen to Hammond swearing at the buses. Or his line "Cycle lane! One... two... three meters of it and now I'm back under that bus..."
Gotta say I wouldn't want to have to cycle in London, although, given how congested the traffic is, at least you'd know the cars wouldn't be moving particularly fast.