Am I allowed to mention Halo 2 vehicles? Because I love me some hot Ghost action. It looks awesome, runs people over, shoots cool plasma, and controls like a dream. Not to mention that the vehicle combat seems a million times more epic when you're using a Ghost to fight off Banshees, other Ghosts, Warthogs, and those giant tanks. There's one section of highway in particular in Halo 2 where I felt just tiny as I zipped along in my Ghost attempting to destroy massive armies of vehicles.
I guess the runner-up would be either the Glider power from Transformers (PS2 only version), or maybe the Jeep from Timesplitters: Future Perfect.