I've been renting with Avis for well over 10 years consistently now and recently had my first issue with EZ Pass. Although the device was closed, the EZ Pass was still being "read" by the toll booths. It happened on day 1 of the rental and the toll collector told me he could reverse the charge on the EZ Pass while I paid him cash. The next day, I pull up to grab my ticket on the Pennsylvania Turnpike and the ticket won't come out but I notice that the EZ Pass light at the ticket machine is green so I quickly understand that the EZ Pass has been "read" once again. As I exit, I ask the toll booth collector if he could reverse the charge and I'll pay cash. He asked if I have a ticket and since the answer was no, he couldn't do it. Anyway, the charge is $2.50 a day even if you only used it for one day as I had a $5.00 charge for that one $3.75 toll .
One thing I did learn from that toll is that you can actually remove the entire EZ Pass from the device as it is stuck via velcro. The toll booth collector actually told me this. I would recommend removing the EZ Pass and putting it into the glove compartment. From this one experience, I learned that eventhough the EZ Pass may be in the protective holder, there is the possibility that it can still be "read".