What I want is a way to rent a car for an hour or two, so that I can leave shopping items or child seats in the car while making stops around town.
I think you're looking at $60 an hour which is not horrible (estimating Waymo avg is 3 rides / hour x $20 per ride)
I assume you mean a self-driving vehicle but if not: https://www.zipcar.com/cities
AAA had car-sharing as a service nine years ago, but it and many of its competitors have closed:
https://oaklandside.org/2024/07/25/gig-will-shut-down-its-ca...