I once had a Pay Later rental that, unbeknownst to me, required that I pick up by Sunday at noon, or something like that. I dawdled -- flight was on time, but I went to a lounge, checked email, made a phone call, who knows. By the time I got to Hertz, it was maybe 1pm. Rental record printed out at a new rate. I objected. Clerk said "You were supposed to pick up at noon." I protested, "But now I'm keeping the car fewer hours, as I'll still return it at the same time." Clerk explained "Rate is higher if you pick up after noon." Clerk to his credit overrode the computer and sent me on my way. I don't know if today's Hertz trains or empowers its employees.

I realize my example is about a late pickup rather than early return. But conceptually I think it's similar.

I think I've also heard of postpaid rentals being repriced for early return. Basic concept there is distinguishing between business customers (who might need a car just Monday to Thursday) versus leisure customers (who visit a city for a whole week, or so some pricing model assumes). Hertz wants to charge the business customers more. I think that was the logic with my "pick up Sunday before noon" rental: Leisure customers rent on Sunday morning; by Sunday afternoon, maybe the customers are business people coming in.

For prepaid rentals, though, it seems pretty tough for Hertz to charge more for a shorter rental. Nonetheless the prepaid terms arguably say they can reprice the rental and charge you more. Maybe that's grossly unfair and would fail a credit card chargeback or small claims suit or arbitration action.