@The O.P, I agree with what Crypt and Bill said. Also, has your b.f always driven that way? Is it possible that he's showing off? Or that he might have some problem with his eye sight that he isn't telling you about, or some issue that he's not even aware of? Ask him to get his eyes checked. If he wears glasses or contacts, tell him to wear them when driving. If he continues to do this, then tell him that you'll do the driving next time!