S18, E4: Jeremy Clarkson, Richard Hammond and James May embark on an ambitious project to build mobility scooters that can tackle the wilds of the British countryside. Meanwhile, the Ferrari FF and Bentley Continental V8 are put through their paces at a unique test track on the edge of the Arctic Circle while May is in Florida where he tests the Fisker Karma and meets up with AC/DC frontman Brian Johnson. Plus, Hollywood star Michael Fassbender is the star in the Reasonably Priced Car.