On paper, the two are incredibly evenly matched. The Audi R8 V8 Coupe does 0-60mph in 4.7 seconds, while the Porsche 911 Carrera 4S manages the same sprint a tenth of a second quicker. The Audi is more powerful, but the Porsche is lighter and more efficient.
In this case, both have slick automatic gearboxes mated to complex four-wheel drive systems, ensuring unbeatable all-weather grip. But which is quicker round the tight and twisty test-track at Blyton?