When I lived and drove in Ethiopia, the worst thing to call another driver was "woosha" or "dog." This seemed odd because Ethiopians in general at least regarded dogs with a benign neglect. After moving back to DC I used this epithet to great effect while bicycle commuting, to curse out the 99% of the cab-driving workforce that was from Ethiopia, when they inevitably cut me off or tried with malice aforethought to kill me.
Here in Jordan, when another driver does something especially egregious (and it's got to be borderline-murderous to even get noticed) you call them a "himmar" or "donkey." Given how Jordanians feel about dogs, you would think they would shout "kelp!" (dog) at each other in order to cause insult. Bit it's not so.
In the US we don't seem to call each other animal names in traffic. At least in the places I've lived, people call each other human body parts.