Honestly, driverless cars are going to reduce the total number of vehicles purchased because: People will be able to subscribe to a car service. It will know your work schedule and have a car waiting to pick you up from home and job. If you want to go somewhere, you just let the app know when and a car will come. If you go to town to do some shopping, it will drop you off. You don't own the car. You don't pay maintenance. You have no car payment. You pay the monthly sub (and it can be different tiers, depending on how much travel time you need regularly.

Once most people start doing this, cities will only need enough cars to support the maximum transit demand at peak times. Some of the cheaper plans will offer rideshare, meaning the car will pick up multiple passengers that are going the same direction. The demand for owning a car will drop as it will be a bigger expense and feel cumbersome in time.

Parking lot space will be reclaimed and repurposed in cities (hopefully by making mini parks with trees and plants). Overall, cities will become healthier (since the vehicles will have cleaner emissions), with the air quality improving. Traffic accidents will be almost non-existent.