I believe the engine is developed in-house this time...
Wiki: "The car is powered by a 3.8 liter twin-turbo V8 with a flat-plane crankshaft. The engine produces approximately 600 horsepower and 433 foot-pounds of torque. It has a redline of 8,500 rpm, with 80% of torque available at just 2,000 rpm. When they announced the car, McLaren claimed that their engine will have a higher horsepower to carbon dioxide emission ratio than any internal-combustion engine available at the time."
It will also be a fraction of the cost of the legendary F1...
"The MP4-12C will be sold at a price of £150,000, aimed at competitors including the Ferrari 458 Italia and Lamborghini Gallardo."
Exciting for sure. Although not so much for broke-ass chumps like me. Hey Bullet Ride can I come over and watch Top Gear? No TV ... :-P