On roads operated by the Turnpike Authority those with transponders receive on the spot discounts at most toll plazas. For instance, on Florida's Turnpike the mainline plaza between I-75 and Orlando charges $2.50 for cars without a transponder but only $2.00 to cars with a transponder. A car coming from Fort Lauderdale to I-4 in Orlando is charged $15.70 without a transponder and $12.40 with a transponder. Most tolls at exits are 25-cents less with a transponder. It doesn't matter which of the Florida-based transponders you have, you get the discount.
On roads operated by the Orlando-Orange County Expressway Authority only those with
their transponder (E-PASS) save and it's not on the spot. You have to spend a certain minimum in tolls each month (I think $50) and then they give a discount/rebate back to the prepaid account.
The transponders last a long time; you won't have to replace it. As far as battery changes go, a Sunpass is easy to open and takes a regular battery. E-PASS is much more difficult to open and you should take that to Orlando-area Lowes for a free replacement. Batteries last many years because power is only used at a toll point as well as at the many traffic density monitoring points on Orlando arterial roads.
Expressway Authority roads include:
TOLL 408 - East West Expressway
TOLL 414 - Apopka Bypass (under construction)
TOLL 417 - Central Florida Greeneway (Orange County only)
TOLL 429 - Western Beltway from Apopka to Siedel Road
TOLL 528 - Beachline Expressway between the Airport and Brevard County
EA toll booths display the E-PASS symbol.
Turnpike
Enterprise roads in the Orlando area include:
Florida's Turnpike
TOLL 417 - Seminole Expressway (the Greeneway in Seminole County)
TOLL 417 - Southern Connecter (the Greeneway in Osceola County)
TOLL 429 - Siedel Road south to I-4 (west of Disney)
TOLL 528 - Beachline Expressway between the Airport and I-4
Their toll booths display the Sunpass symbol.
The biggest advantage of the transponders is not the toll savings (which is good too) but not having to stop to pay. All Expressway Authority mainline plazas now have or soon will have "open-road tolling" where cash payers are diverted onto an side road to stop and pay while those with transponders continue straight ahead at expressway speeds. Sunpass also has this at one brand new plaza on the 429 south of Disney.
BobK/Orlando