Face orientation issues

[mgeurts]

Hello,

I'm trying to make a solid out of a .STL. 

I repaired some issues in the Repair environment but some remains:

Increasing the tolerance resulted in the same message. Does someone know which different method is meant in this message?

Also, when I click on the Intersecting Faces message, Inventor lags for at least an hour, with CPU usage of not even 5% (then I interrupt)

I also tried the file in 3DSMax and Fusion but due to lack of experience it didn't bring me further.

Does someone has a suggestion on how to continue in order to get an workable solid?

I'm on Inventor 2021

[Gabriel_Watson]

Try using Fusion to make this conversion. Inventor is simply incapable of fixing these many issues in a large mesh object:

[JDMather]

@mgeurts 

I see some illogical interference between the muffler and bottom.

Can you ask the source for logical geometry?

The brake rotors do not have any thickness - that isn't logical?

Gaps around the hood, the doors, front headlights?