how to fix a blender model ?

I have a car model that has normal problem. This question has been asked many times in the forum, I believe.

Some faces of the car model are disappeared. I tried recalculated normal outside, but it does not help.

If I set “Doubled Sided” off in blender, I can see blender shows exactly the same problem as in panda.

If I manually flip normal for these missing polygons, panda can see the missing faces again, but blender, render in solid mode, the faces become missing.

What can I do in blender in order to make the blender rendering match the panda rendering (without setTwoSided in Panda) ?

Thank you !

It could be that your model has a negative scale.
In object mode, hit N and make sure there is no negative scale set. Instead, apply any negative scale in edit mode. (Afterwards, flip or recalculate the normals outside again)

I also met this problem once, and this error persisted no matter how I recalculated normals. I am not sure, but suspect it could happen because vertices (for some strange reason) were exported from Blender in clockwise order (while they must be counterclockwise). Again, I am not sure, and the problem definitely requires more investigation.

It seems not a negative scale. But it is a good tips also.

The model is a public one and I believe the original mesh is not correctly created.

I fix it slowly by separating the problematic faces, flip it, and merge them back to the original mesh.