I just purchased an 08 Unlimited Rubicon. I've installed my EZ-Pass transponder to the right of the rear view mirror and an inch or so under the roof line, as their installation instructions say. However, its only actually read once out of the five times I've gone through a toll facility since I got the JK.
I'm guessing that the 90 degree angle of the windshield may have something to do with the problem. If anyone has any better suggestions as to where to place the transponder, it would be appreciated. Thanks.