I have a 3-day leisure trip where I'm scheduled to arrive after 11 pm on a Wednesday night and want to return the car at 11 pm on a Saturday night for a redeye flight home. The rate is considerably more expensive than if I could keep the car until after that midnight on Saturday. What would happen if I book the rental for, say 12:30 am Thursday to 12:30 am Sunday but actually show up at 11:30 pm Wednesday, and then return at 11:30 pm Saturday. Will they recalibrate the rate and remove my "Saturday night coupon"?