Hard to say if anyone on that film were every totally sober. A much better "cannonball" movie is The Gumball Rally. While the Cannonball Run movies do enjoy better production values The Gumball Rally actually gets pretty close to the real Cannonball Baker Sea to Shing Sea Runs. My favorite line from The Gumball Rally is near the beginning, the driver of one car has just gotten here from Italy, he gets into the car and says to his co-driver "The first rule of Italian driving", rips rear view mirror off and tosses it into the back seat, "what is behind you does not matter".
Rent, buy, beg, or borrow a copy of this one, I don't think you will be disappointed.