Concerns about EZPass readers being used to track vehicles prompted an engineer to 'hack' his and render it audible to the owner whenever it is scanned by a reader. He found it was being read by more than just the toll booths.

http://www.popsci.com/article/diy/ezpass-hack-covert-scanning

 

if your worried about someone reading your ezpass, put it in the glove compartment. get it out when getting on or offf the turnpike.
cliff

 

Here in Houston, we have "ez-tag" which is just a sticker on the windshield. It is about as thick as 3 or 4 layers of electrical tape. I don't see how it could have any electronics inside, but I guess it must. I've often wondered how it works, and if it is possible to hack it in a similar way. Any clue what might be inside the ez tag and how it works?

http://traffic.houstontranstar.org/aviinfo/avi-intro.html