Porsche (911 and all S's) - Driving connoisseur
Higher end BMWs - Someone who knows what they want in life
Porsche (non S) - Someone who wears AX shirt with huge AX logo to show off
BMW (lower end) - See above
Ferrari - Either a rich asshole or a driving enthusiast
Lamborghini - Loud showoff with nice taste
Prius - Person with no life
Mini - Affordable and cool. Can't really say anything bad about it really
VW Bug - Either a gay man or a pathetic woman
Merc GL or similar - Soccer mom
Merc S - Retired, 100 yr old grandpa
Audi - I wanted a German car but I completely had no idea what to buy... wears ugly mocassins
350Z - Douchebag!!!!!!!!
Evo/STI - Rice boy unless tastefully modded
Jag - Big pimp
Corvette - Grand dad with more money than sense
Anything normal size with wheels bigger than 20 and chrome - Usually some trash with seat so reclined, I sometimes wonder how do they see over the windscreen :P
Merc AMG especially the E55 - Russian millionaire wannabe