The last two mid-size rentals (since October '10), one at MCI and one at CHO (Charlottesville,VA), using PC's, did result in a higher price on the contract at outbound BUT the billed price at the end of the rental has actually been LOWER than what was quoted on my reservation confirmation. Also, both stations provided upgraded vehicles over the reserved rate and the one at CHO had NeverLost in it. MCI gave me a RAV4 with 60 miles on it.
The only time I EVER recall a final bill coming back with a total higher than the reservation quote, and it's pretty consistent, is at my HLE. Once I point the coupon out to them, they apply it and no problems. They just shake their heads at the 10.00/day rates