Cash Cab (UK)

Contestants go on a unique taxi ride which will pay them if they can answer questions right during the ride. The first three easy questions are worth £10 each, then five worth £50 each. After that, seven questions are worth £100 followed by the big money £500 questions.

Though, three wrong answers means they're dropped off wherever they are. The contestants can phone whoever they like, and even get the help of random bypassers.