Sorry about reviving a sort of dead thread but I had a question regarding this and didn't want to start a whole new thread.

I just want to make sure that your saying if you buy this sunpass, you won't be charged any administrative fees (like $25) a day plus the cost of the toll if you don't pay for any toll type passes with your rental car company when driving on Florida toll roads (like the Florida Turnpike). So all you have to do is go the CVS, but the card and possibly load some money on it and then register the card online and put it on your windshield? Do all the rental car companies have a transponder or something on their windshield for picking up on tolls or only if you opt in for the toll program? I am confused what this transponder looks like and where it's located in the car?