I started taking phenibut in the search for a good sleep aid and have used it occassionally, normally at night in dose ranges of 200 mg to 1.5/2g. I would describe it's effects( when they finally arrive) as likened to 'dirty' xanax. It puts one in an interesting mental space, something akin to the painful raised awareness of the true potential of the human mind as experienced through fog. It made me lose my filter, thoughts move faster and in more angular, exponential, or recursive logical schemas which have exponentiated the ability to use my already present wry sense of humor.
I can alternate between concentrating on the feeling/noticing that i'm messed up with noticing that i can still think and better even combined with the fact that i'm not really messed up.
Like xanax, inhibition and anxiety are gone so you speak more freely and sometimes more bluntly without being mean: insulting through well buried sarcastic comments, making jokes that only the very acute minds grasp.
With regards to driving one would think that it would be dangerous, and I do not condone others to do so.
It did allow me to become more hyperaware of the road increased the function of every sense. I drove the crowded streets safely but like mario andretti at the same time. It basically enhances the speed of cognitive function if nothing else.
I after consuming 1-2g over three days experienced a persistance of mental function/anxiety reduction, during which any driving was actually performed.
It's very wierd though these effects could 'drive' one to continue use.