Many have reported that their toll transponders won't work from inside the Tesla. The solution provided by the Tollroads Authority is to give you an external transponder. However, this will not work with I-110 and I-10 toll lanes in Los Angeles for free tolling. You need the internal model with the three position switch, set in the "3" position. My July build has a solid black area to the right of the rear view mirror at the top of the windshield. Like others, I had tried holding it there and found it did not register when passing the toll readers. However, the issue is positional. Placing the transponder with the switch closest to the rear view mirror, it reads 100% of the time. Any other positions, it fails 100% of the time. Hoping this helps those who commute in LA and the OC.