Just in case this ever happens to you...today I tried to reserve a car through Concur using the usual workflow along with air and hotel reservations. At the reserve a car phase of the flow, Concur showed that both National and Enterprise had no cars available. Concur did offer a minivan from Avis for two days for a whopping $265. I thought...OK...for what I'm doing it's time to enroll in Uber then to save SAS some money. Then I immediately went on to my National car app on my phone (which is tied to the SAS contract with National) and tried to rent using that pathway. Rental went through as needed...estimated total $62.26.