Has anyone actually met a "smug" Prius owner? Because I know a few, and none of them are smug. (Or self-righteous" or "greener-than-thou" or etc etc>) Pleased, perhaps, like anyone who whatever that they like, but not smug. It seems like another of those things that's based on a common lazy journalistic meme but has little or no connection to reality.
On the other hand, I have actually met a few smug -- and/or hair-trigger defensive -- SUV owners, and a couple of Hummer owners who were so far beyond smug that I'm not sure there's a word for it. (Obligatory head-pat to SUV owners -- yes, I know some SUVs are driven by people who actually have a good use for such a vehicle, and yes, that's absolutely an individual's decision to make.)