The McLaren MP4-12C is already an unbelievable driving experience and one of the fastest cars money can buy. And for 2014, it's getting more powwwerrrrrr. (Update: Actually not.)
I had a chance to drive the 12C Spider yesterday (more on that in a bit), and while I was doing a chassis walk around with engineers, I confirmed that the engine of the P1 shares some architecture with the 12C. It's heavily revised, of course, which is how it pushes out 727 horsepower.