motarded adj. excessively stupid; in the military, enthusiastic to the point of stupidity. Editorial Note: Although there’s no shortage of jokes, puns, and misunderstandings about its similarity to “retarded,” a different “motarded” comes from motocross racing, in which a certain kind of motorbiking is known as a Super Motard, French for “super biker.” Andrew Trevitt has a good explanation of the sport in Sport Rider magazine. Motorbikes modified for professional racing but ridden on streets by amateurs are sometimes called “motarded.” Etymological Note: Perhaps from moron(ic), motivated, or more + retarded. (source: Double-Tongued Dictionary)
I like this word, but I think it could be expanded to apply to all the motarded drivers on the road.