We need to rent a car for 10 days for our upcoming vacation... I've found great weekly rates, but the three extra days are killing us! Would I be able to rent the car for a week and then do a separate reservation for the last three days, which are weekend days, to get a lower rate on those days? Will I have to return to the rental place inbetween or would they let me check in for both reservations at once and keep the same vehicle the whole time?