http://youtube.com/watch?v=pTd0reK4I-o
http://youtube.com/watch?v=MdyGUt1PpgA
http://youtube.com/watch?v=oLTiaq1nx1Q
Dollar for dollar, bikes will usually win, at least against road cars, but most of that is because road cars are weighed down by things that bikes simply don't have, like spares... or roofs. Unfortunately there are not a whole lot of companies that produce extremely pure sports cars a prices comperable to a R1 or whatever they quickest bike is nowadays. I'm not talking Miatas here, I'm talking Ariel Atoms, the really hardcore stuff.
On the highest possible end, cars win hands down no questions asked. Compare Moto GP track times to F1 track times (yes, its the same circuit)-
Moto GP Shanghai lap record- 1' 59.318
F1 Shanghai lap record- 1' 32.238 (Michael Schumacher)
The F1 car blows the Moto GP bike away.
So in theory, throwing out money as a concern, cars are faster then bikes.
Throw in money, and a bike will win the majority of the time.
Throw in less then perfect weather, it goes back to the car.