Pods and Self-driving Carriages
I'm not convinced we'll only want to rent self-driving taxis. There are benefits to having a car with personal space: leaving things in your car such as a sweater for when a restaurant puts the AC too high, or storing packages purchased in different stores while out shopping, or simply having confidence that if you accidentally leave something in the car it'll still be there when you go back. But there's a possible compromise. Design for separable carriage and passenger/cargo pods. Your personal pop sits along the street or in a garage. You order a shared carriage, then sit in your pod to relax and listen to tunes, or start working. In a few minutes a generic taxi-carriage comes along, slides under the pod to pick it up, and drives off with you. There would be security features so no one else can order a carriage to pick up your pod from the street (i.e. steal it). You could order a carriage with better range for long trips - more flexibility than a normal car.