Hummmm! All of them are mounted on the windshield here.
Where to mount EZ Pass instructions Isn't there someplace else I can mount my E-ZPass other than the windshield?
No. The transponder should be installed approximately one inch below the top of your windshield above your rearview mirror as stated in How It Works: it may not be "read" by the E-ZPass antenna. Placing the transponder on the sun visor, the rear view mirror, the dashboard, the seat, or in your hand may work sometimes, but will not work all of the time. Installing the transponder incorrectly or not at all may cause unnecessary toll evasion violations, administrative fees or delays at the tollbooth.
RI also say mount on windshield. NOT where yours is mounted.