On this very special episode of Head 2 Head, The titans of this century come together!  Presenting a hypercar battle for the ages: the McLaren P1 versus the Porsche 918 Spyder. Both of these cars have carbon fiber tubs and body panels. Both have small displacement, high revving V-8s packed between their passenger compartments and rear axles. Both use twin-clutch transmissions, carbon ceramic brakes, and active aerodynamics. Both have roughly 900 hp. Both are plug-in hybrids. And today, with the help of pro racing driver Randy Pobst, we find out which one is fastest around Mazda Raceway Laguna Seca!