I'm not sure that you would be on any toll roads from MIA to the keys. From the Keys to Naples, you'll need $2.50, I-75/Alligator Alley. No tolls from Naples to Tampa on I-75.

Doing what you're doing, I can't imagine how you could spend $6.99 total, yet alone that much per day. You may have a smallish toll getting out of Miami, depending upon your route, including the Florida Turnpike a short distance if you choose to take it towards the Keys, but no tolls to the Keys or in the Keys, and coming back from the Keys towards Naples as well as all the way up to Tampa there are NO tolls. (Do not take I-75 from Miami to Naples which does have a toll, but take US 41 (Tamiami Trail) which has no tolls and is much better, shorter, and more scenic anyway.

Sorry, guess we overlapped, but again I'd highly suggest taking US 41 to Naples coming back from the Keys and not going way up I-75 towards Ft. Lauderdale and then across the state to Naples.

I have turned down this option when I have been offered it in California. My guess: car rental companies would not offer pre-paid toll unless it were a money-maker for them.

HTTY

Stay OFF the Turnpike around Miami, period.

Ask the car company what will happen if you refuse the toll tag option but "accidentally" go through a no-cash toll booth. I assume you will get charged the toll plus some sort of service charge from the rental car company, but find out what it is (it would have to be in the rental contract, I would imagine). If memory serves me right there are at least two but no more than three toll boothe going the fastest way from the airport to the Keys (BTW you didn't mention where you would be picking up the rental car, for this post I'll assume the airport). Then as others have mentioned you should not have any more tolls. So if the toll plus service charge are drmatically less than 6.99/day for at least 7 days, it is an easy choice-decline the toll tag but go through the booths anyway and let the chips fall where they may. 3 years ago I rented a car in Philly and drove to the Jersey Shore for a weekend, on the way back to PHL I accidentally went through a toll-tag lane on the Walt Whitman Bridge and expected to see it show up on my rental car bill. It didn't, but then I expected some sort of charge to show up later on the credit card I used to rent the car...it never did.

I'd also like to comment on the person who said to stay off the turnpike around Miami. MIA to Key Largo, taking the turnpike, will take about 1 hour during average traffic. The same trip taking US1 (the easiest route for those unfamialr with Miami) might take almost twice as long.

This is a money maker for the rental car co's - don't do it. All the cars I've seen have the toll tag concealed in a box on the windshield. You need to open the box to use the tag, otherwise the metal box shields the radio frequency transmission.

Our transporter is just a sticker on the windshield. No boxes, no batteries, no need to open anything. www.sunpass.com, look it up.

That said, the OP should not get the box. We paid $15.34 for the sticker and that included about $15.00 in credit when the sticker arrived. We do get a discount of 25% anytime we use any toll roads in Florida. The sticker pass is re loadable on line so no need to purchase any more, just recharge when it's getting low.

Here is the information you need to make an informed decision about driving a rental car (or truck) on Florida toll roads.
https://www.sunpass.com/rentalcar
You will note that some rental car companies have a $2.95/day fee plus tolls. If you rent for more than 5 days up to 30 days, it is less than $15 for the month.
You can get to nearly any place in Florida without paying a toll. It may take you a half hour longer but you can get there.

Thanks for all your imput. The rental car company says it will charge an administrative fee of $25 each time on top of the toll charge (what a rip off) if you don't buy their toll package. I was hoping to avoid the toll roads completely which sounds like i'll be able to thanks to all your help.

What company are you using that's charging $6.99/day? We rented a car from Budget and drove round trip from Ft. Lauderdale to Key West right after Florida instituted the no cash toll rule. We were charged a daily fee plus the tolls, but I'm pretty sure it less than $7/day.

Since we were only renting for 5 days, it was worth it to us to have it rather than risk their "administrative fee" in case we went thru the tolls (which we did).

Do what NeoPatrick says.

It's called a Sun Pass, see if you can purchase your own. Its attached to the windshield of the car and the toll registers as you drive under them. It saves you a quarter each toll. Each toll is 75 cents with a Sun Pass.

I thought I explained that part virginiaomatic...

Yes, AAFF, you did. But why virginiaomatic is suggesting the OP actually buy a Sun Pass for this scenario is beyond my imagination!

Hi to everybody!
I'm going to have a tour of Florida in one week... We are going to rent a car in MIA Airport and then (after 3 days in SOBe) my family and I will go up on the Gulf Coast - our goal would be fort mayers and pensacola.... So this topic of TOLL roads surprised us a lot: last trip to florida everything was free,....So now we do not know what to do yet... Car rental agency of course would sell a Sunpass but, still we do not know if it will be fair to have it... we read that from airport to MIA all roads are toll, have you any ideas or suggestions?

Did you read the above responses? No, it makes no sense to buy the SunPass with the car rental. You may spend us much as three or four dollars total on tolls. Big deal. Those are short toll roads only -- not major tolls like cross state turnpikes -- with the exception of traveling on Alligator Alley from Ft Lauderdale to Naples which will set you back a whopping $3. But I would suggest you take the much more interesting and scenic Tamiami Trail (US 41) anyway which is free!

Please just listen to NeoPatrick.