About the amount of detail, I'm not going to give my C&C since it's obvious that the model reflects reality thus nice job there
But off course, it wouldn't be plausible towards the framerate when lets say you want to make a Moto GP-like game. Since mostly you would have got around 15-20 bikes which means around 1335000-1780000 polies without any game environment or code yet

I think, from my pov, it's best to keep it to your intial idea.
My point is not to look down at you but to give constructive C&C thus the best option would be a screensaver. And you got to admit, that would be one heck of a screensaver right ^^

Cheers

Frazzle