We have a guide available that helps with troubleshooting glass collisions: Troubleshooting Glass Collisions
Normally, all that's necessary is to set the ID and attributes in polygon mode and add the user defined options to the collision object and the glass materials.
I tried that already and its still acting as if the objects are made out of metal around the areas where the glass is.. I'll check the troubleshooting guide and see if maybe there's anything else in there that I haven't tried yet
Update: followed steps listed in the troubleshooting guide and still no changes - model was initially made to be a gang vehicle with bullet proof glass but i've taken the flags out and tried everything i could think of and I'm sure there's a way to fix it but I don't know what else to do to try and fix it