Tiff Needell and Jason Plato pit the Nissan GT-R against the Porsche 911 Turbo, hoping to prove the new supercar can match the speed and power of its glamorous rival. Vicki Butler-Henderson examines the BMW 6 Series convertible in southern Spain, and Jonny Smith offers advice about how to tackle the Nurburgring race track in Germany. The team also tests Peugeot's new 508 mid-sized saloon.