If I had to pick one group -- it would be "tuner" drivers. Doesn't matter what brand, ass soon as you put a tuner wing on and and chop a couple of coils out of your springs, you apparently forget how to drive. (The exception seems to be people with "real" tuners, who seem to be just like us Mustang people -- don't really need to prove anything.)
And (sorry Bruce) Prius owners who "hyper-mile" and treat their average mpg meter like some sort of "I'm Special" award.
(At one point I was gonna get a license plate frame that said "My Cobra burns the gas your Prius saves")