I drive high everyday, and i've never been pulled over, or been in ANY crash, and i've only come close to a crash once, and that wasnt anything to do with me being stoned - i was rolling the joint to get stoned.
Anyway, i try not to roll, but stoned normally i can drive fine. I've been doing it for so long now almost everyday, that my perceptions are all fine, i can still judge speed well, spaces and time.

But i wouldnt advice anyone to drive REALLY fucked. If i get really fucked i lay down in the back of my van for an hour or two untill im good to go.