Oh come on, are you seriously saying that using a derogotary term makes kids want to be that. I could just as easily label them braindead t**ts, by your logic all the kids would go 'Yeah I want to be a braindead t**t too'. Of the kids I know they REALLY don't want to be chavs because its a negative thing.
As for what do I consider dodgy cars, basically any car that they spend all their time bolting cheap bits of plastic onto.