Overview: Being a taxi driver always ranks among the most challenging jobs in the country, so the guys head to Las Vegas on a quest to create the ultimate taxi, aiming to keep both driver and passengers happy. After getting some experience riding along with real cabbies, they reveal their creations, put them through a series of tests and then hit the Vegas strip to see who can get the most tips. Then we review the newest supercar to come out of the UK--the McLaren MP4-12C, and see how it stacks up against a good old American NASCAR Cup car.