Does buying a Prius make you stupid, or do stupid people buy Priuses? (Prii?)

The Toyota Prius has become the bestselling car in California [LA Times]. It makes a bold fashion statement that the owner is eco-friendly.

Of course, it also makes the statement that the owner is not facile with basic ROI math. Even at the currently outrageous gas prices, it will take more than 6 years to make up for the approximately $5,000 up front premium over an equivalent non-hybrid vehicle [Edmunds].

But this rant is about driving skills, not math.

Even now, the Prius is less than 4% of new car registrations, and so much less than 4% of cars on the road. And yet, about 20% of my experiences with bad driving involve a Prius, whether in my car or on my bicycle.

Incidents include drifting into the bike lane, turning without signaling, driving ridiculously slowly, being overly cowed by speed bumps, and generally driving like a turd.

Doesn't anyone notice this!? I feel like I am taking crazy pills!

On the plus side, Prius owners park well.

Now, the Prius demographic does trend toward the ancient citizen. Old people, in addition to smelling funny and wearing diapers, are not renowned for good driving. As if to give a wrinkly finger to youngsters, they periodically drive into a crowd of children while claiming they stomped on the brake pedal.

Prius owners may suffer from "moral licensing", where feeling like they are saving the planet causes them to act less altruistically in other ways [source]. The same phenomenon is observed of people who buy organic foods. In a recent study, hybrid drivers were less likely than most to yield to pedestrians in a crosswalk.

Prius owners (and hybrid drivers in general) get more tickets [I can't seem to find the original source, but it is referenced often].

But, the original question still stands. Does buying a Prius make you stupid, or do stupid people buy Priuses.