> (ie. A few floors of underground parking under every building)

Have you actually thought this through?

For example - 6,000 people work at the Gerkin.

Can you guess what area is needed to park 6,000 cars? How many underground levels you'd need? How long would it take cars to filter in at the start of the day and filter out at the end? How much road space you'd need for everyone to get to the building in the first place?

It's 90,000 m^2. That's about 90 underground levels you're building there, or digging twice as deep as the building is high.

Your idea is insane.

You appear to be shadow banned, but this comment is spot on. Cars do not scale well in urban areas because the space taken per passenger on the road (and when parked) is far too big.