Hi @cyrus_costa, we’re deeply sorry for the (very) delayed reply.
Our team was going through some restucturing and now we are trying to reply to all of the unanswered forum posts from moths past 
I’m not sure if I completely follow what you mean. If you mean to run an aerodynamics simulation, unfortunately the only way you could do that is by modelling the external aerodynamics case, as per in the following tutorial:
However, if you want to simulate something like the airflow inside the car, you could run an Internal Aerodynamics simulation like this:
I hope that helps!
Best,
Igor