Try these steps to see if it fixes the problem.
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Your car needs to be one mesh (the wheels and chassis need to be one object) (side note: you wouldn’t do this if you intend to swap the wheels with other assets. In that case you export the wheel separately) skin each wheel bone to only control its wheel.
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Make sure your scale is 100,100,100 before skinning.
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when you import in, make sure there are no files of your previous failed attempts, this can confuse the engine when bringing in assets of the same name. Clear that data before exporting+importing again until you get it right.
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Don’t import animations, you only want to create the skeletal rig, animations should come in separately.