I'm not the first to think of this idea, but in my series of essays on self driving cars I thought it would be worth discussing some ideas on suspension.
Driven cars need to have a modestly tight suspension. The driver needs to feel the road. An AI driven car doesn't need that, so the suspension can be tuned for the maximum comfort of the passengers. You can start bu just making it much softer than a driver would like, but you can go further.
There are active suspension systems that use motors, electromagnets or other systems to control the ride. Now there are even products to use ferrofluids, whose viscosity can be controlled by magnetic fields, in a shock absorber.
I propose combining that with a scanner which detects changes in the road surface and predicts exactly the right amount of active suspension or shock absorption needed for a smooth ride. This could be done with a laser off the front bumper, or even mechanically with a small probe off the front with its own small wheel in front of the main wheel.
As such systems improve, you could even imagine it making sense to give a car more than 4 wheels. With the proper distribution of wheels, it could become possible, if a bump is coming up for just one or two of the wheels to largely decouple the vehicle from those wheels and put the weight on the others. With this most bumps might barely affect the ride. This could mean a very smooth ride even on a bumpy dirt or gravel road, or a poorly maintained road with potholes. (The decoupling would also stop the pothole from doing much damage to the tire.)
As a result, our self-driving cars could give us another saving, by reducing the need for spending on road maintenance. You would still need it, but not as much. Of course you still can't get rid of hills and dips.
I predict that some riders at least will be more concerned with ride comfort than speed. If their self-driving car is a comfortable work-pod, with computer/TV and phone, time in the car will not be "downtime" if the ride is comfortable enough. Riders will accept a longer trip if there are no bumps, turns and rapid accelerations to distract them from reading or working.
Now perfect synchronization with traffic lights and other vehicles will avoid starts and stops. But many riders will prefer very gradual accelerations when starts and stops are needed. They will like slower, wider turns with a vehicle which gimbals perfectly into the turn. And fewer turns to boot. They'll be annoyed at the human driven cars on the road which are more erratic, and force distracting changes of speed or vector. Their vehicles may try to group together, and avoid lanes with human drivers, or choose slightly slower routes with fewer human drivers.
The cars will warn their passengers about impending turns and accelerations so they can look up -- the main cause of motion sickness is a disconnect between what your eyes see and your inner ear feels, so many have a problem reading or working in an accelerating vehicle.
People like a smooth, distraction free trip. In Japan, the Shinkansen features the express Nozomi trains which include cars where they do not make announcements. You are responsible for noticing your stop and getting off. It is a much nicer place to work, sleep or read.