Metal Oxide Windshields
Some vehicle models are manufactured with a metal oxide windshield. These metallized windshields will prevent the tag from successfully communicating with the roadside system. Some manufacturers of vehicles with metallized windshields will leave a small metal-free area specifically for the installation of RFID tags. These metal-free zones are not visible to the naked eye; however they are typically located close to or behind the rear-view mirror. Please confirm this location with your vehicle’s manual and/or your vehicle’s manufacturer. For reference, the Bay Area Toll Authority maintains a list of vehicles with metal oxide windshields:
https://www.bayareafastrak.org/en/common/docsMetalOxideWindshieldList.pdf
(NOTE: This list is not maintained by the IBA and may not be all inclusive. It is provided as reference only. Owners should always check vehicle owners manuals first)