I am the exact opposite. When I am high, I am paranoid, I drive slow, and I second guess and overanalyze. This is not good for driving, and I have made dumb mistakes while driving high like stopping at a green light, going 10 to 15 under the speed limit, and getting lost. However, I am at least aware of my impairment which is why I am so nervous in the first place.
When I am drunk, on the otherhand, I play my music loudly, and I generally am overconfident and oblivious.
The other major difference between the two is the amount that I take and drive. When I smoke a little bit of weed, I am like, okay I am fine to drive, and when I smoke too much I am too scared to drive.
On the other hand, when I drink a few beers I know that I shouldnt drive, and I dont. Even though I am capable of driving safely, I know that my BAC is probably over .08. Skip ahead to when I am 6 beers drunker, and I am like, fuck it man, I can drive right now, sheeeeet mayne, turn up the music.
I have only driven fucked up a few times, but I always regret it no matter what I am fucked up on.