Step-by-Step Tutorial Session 2 - Full Car Aerodynamics (Part 2)

Hello,

I have been working on this HW for a couple of days now, I really enjoy it and appreciate this course. Yet, I have been having problems with my simulation, for some reason, it fails. The first time it failed after very little progress and I found a mistake. After I fixed it the simulation progressed to nearly half and failed again. Since then I have not been able to find more mistakes.
What do you think could be the problem?
The link to the project:

Thanks in advance,
Yael.