Does anyone know if the trunk lip on my 2012 e550 act to increase downforce on the rear of the car or to lower drag by smoothing the separation of airflow at the rear of the car? Actually, same question about the lip on the roof?

I ask because if it's about downforce, I'm wondering if I can remove it and use a diffuser under the rear bumper cover to generate the same downforce, and remove the trunk lip.

 

honestly i think its all just for looks... lol not about any downforces or anything

 

Diffusers on our cars are for show. They don't work unless the car is really really low and the underbody is flat. Most diffusers on production vehicles are fake. That being said, you're going to need a spoiler to increase downforce.