Its NOT gonna happen!

Anyway... what if when Hayase turns out to be Mach, Drive explains to him about Chase. Despite what Chase always does when going after Drive, Mach sees him as his "competition".

If Mach and Chase get trapped in a jam somehow, they'll be forced to work together and THAT'S when their two bikes combine into a special vehicle.

what about this: the roimudes created mashine-chaser to fight proto-drive, but seeing the fast development of drive and his Powers they make a New, stronger, verition: Mach. and that is why the bikes combine.