Overview:Jeremy, James and Richard look at the latest range of off-road toys: quad bikes, hovercrafts and buggies; James travels to Dubai to test the fastest four-door saloon in the world - the Bentley Flying Spur, and the BMW 5 Series diesel is compared to the petrol version. Richard travels to Iceland to see if a jeep can drive across a lake Davina McCall is this week's Star in a Reasonably Priced Car. F1 driver Mark Webber also sets a lap-time in the Liana.