I recently rented an Avis auto at the Denver Airport and drove up the 470 toll road to I25 North... Not far... Maybe 40 miles.
Fees automatically charged to my credit card were $3.15 upon entry and another $3.15 upon exit.
Additionally charged a Convenience Fee of $14.75.
Total of $21.05 to go about 40 miles
Travler BEWARE and Wary !