Plus, when you register your sunpass account online, you should register your rentals license plate: if the transponder fails, then your sunpass account will get charged. The charges won't go to the rental company unless the transponder does not work AND the license plate cannot be matched to a valid sunpass account.
Originally Posted by
jackal
my experience, at least, is that you don't need to peel it off and permanently stick it, though most people do recommend getting the portable transponder (for $20) if you plan to use it in rental cars.