Went to Dallas in Sept 2011 and rented a car to drive approx 300 miles from Dallas. We were told at the counter that tolls cannot be paid on the road anymore and it would cost us an extra $10 a day to cover toll charges in the North Texas area. As we were there fore 12 days it would cost us $120. We asked if it was possible to pay for day one and twelve as we would not be in the area for the other days. We were told no, the desk agent asked if we had a route planned we said yes and showed her, she highlighted a route on the rental company's map and told us that tolls would not be charged on that route. Two months after we got home we got a toll violation from the rental company for going through 7 cameras. Total toll charges were $10.05 but admin charge was $25 per event total $175 + toll charge. We have complained to the UK based company we booked the car rental with and await their response.
If we had paid the $10 a day ($120) the actual tolls were $10.05, that is a hell of a mark up.

Be warned if renting cars in Dallas