I see this kind of thing a lot. It's also the reason why I give extra caution at junctions if I'm on a pushbike - not that I am saying you did anything wrong mind :)
It's a merc. For some reason 90% of owners think the world owes them something and they are better than everyone else.
When you see the badge, chances are the driver is the biggest prick you will meet today. Treat it as a warning and your day will be better.
The muppet tailgated me 3 times, did an illegal overtake, cut me off, and is driving around with no MOT