Oh yes, you want Americans. Specifically, get an American (I like the idea of Richard Petty, or Jeff Gordon) or a Canadian (Christopher Plummer would do nicely) to play Number 3 on the leaderboard.
We can then reveal the essential British character as being "ambitious but rubbish," as James uses his best Churchillian to voice to urge his fellow British celebrities to knock Tom, Cam and Chris down from the medal finishes. They'll fail, of course. Jay Kay - fail; Simon Cowell - fail; Gordon Ramsay - fail; Jodie Kidd - fail. Failing - because the quality that makes them think they'll win (being British) just ain't good enough anymore.
Remembering that Jonathan Ross moving is why TG gets all the stars on BBC2 these days, whom else can I think of?
Martin Freeman -- because Sherlock doesn't drive.
Robert Pattinson -- still can't figure out why he shouldn't.
Charlie Boorman -- just to agitate Clarkson about the virtues of motorbikes
Keira Knightley -- to ask JC just exactly what he meant about being a board with a face
Kim Cattrall -- doing theatre in London, right?
Gillian Anderson -- well, we know she's been anxious about it, but
Oz Clarke -- so JC can ask "what were you thinking of, romping around with James May?"
Philip Hammond -- c'mon, it should be a standing order that the Transport Minister should do a stint. Besides, it should go for a fresh round of Hamster jokes.