DTM Car Rear Question

[Jezziem]

Hi,
I always wondered what these "boxes" behind the rear wheels on current DTM cars are for. Since I don't even know what they are called, I didn't find anything online or on other racecars. Are these some some areodynamic magic devices or how can you look at it? Also noticed that there are additional holes on the Mercedes car.

Source of the image:
http://www.rssportscars.com/photos/cars/2014-bmw-m4-dtm/bmw-m4-dtm-h2.jpg

 

[Andrew Harper]

Ok, here's my guess although it may be incorrect!

Looking from the rear maybe the extensions allows the air to flow across the rear panels more cleanly once it passes the rear wheel arches.

If there was a "full on" arch there the airflow would be disturbed once it passes the wheel arch.

The small area at the back is angled upwards so therefore it's acting almost like a dive plane but at the rear. It also acts as an extension to the rear diffuser. If you look underneath you'll see that the diffuser itself is beyond the width of the rear bodywork and its practically the full width of the car. There's a main part and also side pieces as well.

The only other reason I can think of is safety? It may form part of the rear crash structure as well.

I'm only surmising but good fun guessing!

As with these things though it's more or less regulations and what you are allowed to do. For some reason the DTM cars are "allowed" whereas other GT cars I've seen don't seem to have it. Although the Super GT cars have a similar sort of treatment. Notice if they extend the rear arches outwards it allows a wider diffuser, and more downforce?

 

[Jezziem]

Thanks for your thoughts Andrew! It seems that there is no official information on this, just speculation. I will keep you updated, if I enlighten myself.