I’m one of those guys that, in a 15 foot long car will merge into a 16 foot gap. It’s especially fun if the guy on the back side of the gap was trying to gut me off.
And sometimes I’ll go for the 14 foot gap. They always hit the brakes. The key is to act like you don’t see them. ;-)
Rules of the Road, Miami Style:
If you clear the other guy’s front end by more than 18 inches, you really haven’t cut him off. From 3 to 17 inches is questionable...less then 3 inches is considered rude! /s;)