I suspect confirmation bias is heavily in play here. You think Mercedes drivers are more likely to violate road norms than other drivers, so whenever you see a

I suspect confirmation bias is heavily in play here. You think Mercedes drivers are more likely to violate road norms than other drivers, so whenever you see a Mercedes driver, you think, "Ah ha! Another Mercedes driver that's a jerk!" To be honest, I don't see the problem that either you or the author sees with Mercedes drivers. In my experience, it's Audi drivers that are more likely to be jerks than Mercedes drivers, but again, that's probably confirmation bias talking.