EDIT. N.B. This isn't a thread that I started, despite this apparently being the first post. It was split off by the mods from another thread. I don't mind, but I wouldn't like others to think I started a thread just to crow about helping to get a drunk driver convicted. END EDIT.
Fast, for a drunken driver.
In the past, when I used to do a lot of driving late on weekend nights, I assumed that one sign of a drunk driver was very slow driving. On several occasions I'd call it in to the police, and follow the car, if asked, till they arrived.
I don't know what my total count for getting drunk drivers prosecuted was, but at least one, as I had to give a statement to get that one up from "drunk in charge" (when the police saw him) to "drunken driving" (when I did). He was driving slowly and wandering. Mind, that wasn't at night, it was at 12:00 on a weekday lunchtime. Pillock.