It appears that there is no specific prohibition against polycarbonate windshields for cars. The exemption in this case is required because the polycarbonate wi

It appears that there is no specific prohibition against polycarbonate windshields for cars. The exemption in this case is required because the polycarbonate windshields that Terrafugia currently uses do not pass the required abrasion tests: basically, they scratch too easily and are too prone to reduced visibility. Terrafugia requested the exemption because it is still searching for a vendor that passes the compliance tests and meets the vehicle's unique requirements. Apparently, vehicles with the current windshields will be required to undergo regular and frequent inspection and repair. See the page numbered 38273 in the PDF: http://www.terrafugia.com/pdf/2011-16222_NHTSA_EXEMPTION_GRANT.pdf http://www.terrafugia.com/pdf/2011-16222_NHTSA_EXEMPTION_GRA...