Jeremy finds out if a BMW 5 series diesel measures up against the 5 series petrol. In Iceland, Richard finds out if a Jeep can drive across a lake. In Dubai, Jeremy road tests the new Bentley Flying Spur, the fastest four-door saloon in the world. Top Gear looks at the latest range of off-road toys. Formula 1 racing driver Mark Webber joins Jeremy in the studio and TV presenter Davina McCall (UK Big Brother) is the Star in a Reasonably Priced Car.