Having smoked a bong with the person I'm staying with last night, I can say, there is no way I could have safely operated any vehicle. I had a rush of thoughts and was trying to analyze them all, I felt like there was some gravitational pull on me and my vision was moving at 2 frames per second.
I couldn't even control my speech very well and I remember my friend laughing at me because I apparently stopped speaking mid sentence.
Alcohol on the other hand, I feel I could operate a vehicle with, but wouldn't care to try and I get super depressed, irritable and sleepy.
To be honest, I'd prefer pot, because the entire time I felt so happy and was laughing at nothing.