I tried doing a search but couldn't find anything so sorry if this has been addressed somewhere else.

What happens if I return a car late on a weekly rate but I'm only renting for less than a week. For instance, I book a 5 day rental that uses a weekly rate. I return the car 12 hours late so it's effectively a 6 day rental but still less than the weekly rate. Will I only be charged for the increase in daily surcharges or will I be charged for another day even though I've had it for the less than the weekly rate that I paid for?