When I see a car all done up and someone playing loud music with there window down the first thing that comes to my head is try-hard. But other than that no I don't judge anyone by the type of car they drive unless its someone specifically seeking attention through burnouts/loud music or putting on a hell lame number plate.
I would likely stereotype you as some one on the geeky side...I have worked in the video game industry for over a decade and have been around plenty of geeky types and tiny cars are a favorite with them for some reason. I've been in my share of Mini Coopers.
I myself don't like tiny cars because I'm somewhat tall at 6'1", I need my room, and because if you wreck you die. Who cares about your awesome gas mileage when a collision will end you? That's just my perspective though.