I rented a car through Costco a couple of times over the holidays. When I made the reservations online at Costco Travel, I was able to make the reservation through my Costco account, but in my husband’s name since he would be driving. It even stated online that you can make the reservation in someone else’s name. I also was told when we were at the
Enterprise car rental counter picking up he car, that spouse are automatically covered as a driver. However that may have been an Enterprise rule, not a Costco rule.