I know this isn't a constructive comment, but most psychologists and sociologists recognise that stereotypes wouldn't exist if they weren't true to a certain extent. What the
OP witnessed is a stereotype in the flesh.
Oh and just to back up my claim, according to this article, 50% of hoon vehicles impounded in Vic were Holdens...
http://www.perthnow.com.au/news/car-...-1225898002426