Porsche 911 Turbo vs Nissan GT-R vs Audi R8 V10

New Porsche 911 Turbo vs Nissan GT-R vs Audi R8 V10. Which car wins our flat-out super test? Find out more at http://www.autocar.co.uk/porsche, http://www.autocar.co.uk/audi and http://www.autocar.co.uk/nissan