If you look closely at the Mercedes, there appear to be traditional wheel flaps behind the angled ones. The angled ones are also not vertical to the ground, but angled back as well.
I think the idea is to get a good portion, but certainly not all of the air flowing away from the tires, under the body, and what air is not channeled toward the vehicles center is deflected with the traditional flap.
But the key being the air is directed around or away from the tire. In your first photo, you can see nearly the entire tire is exposed to high pressure flow, and the left side of the "v" (when looking at the photo) almost appears to direct air into the tire.
Part of your problem is not your fault however, your car appears to have a very wide and aggressive stance, as the bumper does not even meet the tire. Your car looks like it might benefit from something like the "reverse mud flaps" seen on the prototype Tesla roadster.
