Depends on who you're with and how many are in the server. More people=more chaos which means you'll get hit no matter what.
After the carnage of turn1/lap1 there's usually 2 or 3 guys chasing each other down for the win and one can't blame them for dodging the wrecked cars because they're fighting for position. It is a race after all, albeit a very dirty one.
But if you're out of contention for the win there's no excuse for tooling around and not hitting anybody. (a) its boring, (b) it gets people pissed off at you.
So, IMO, general etiquette of Bangers:
- If you're fighting for the win, go ahead and race
- If you're out of contention (and by that I mean the leader is more than a straightaway ahead of you), CAUSE CHAOS!!!