I didn't realize there are 2 billion cars out there:

According to Elon’s estimates, there are more than 2 billion legacy cars on the road, globally. Currently, the car industry can only produce around 100 million new vehicles a year. Just from a manufacturing perspective, it could take 20 years to build a new fleet that approximates the one we have now. 

I look forward to living in this world.

Autonomous vehicles equipped with lasers, infrared sensors, cameras, detailed 3D road-maps, and other technologies are able to assess their surroundings in ways that human eyes can't. They can detect objects behind walls. They can accurately estimate distance at speed. They can brake and accelerate faster than humans can and change direction with more precision. They don't drink and drive, text and drive, nod off six hours into a long trip, or experience road rage.

But it’s not just the capacity of autonomous vehicles to make a fairly safe activity even safer that makes them so transformative. It’s that they will substantially reduce fatalities and collisions while simultaneously increasing overall transportation efficiency and decreasing our need to pay attention while driving.

If thousands of human-controlled cars suddenly started traveling down highways at 90 MPH, with little space between their bumpers, there would certainly be a lot more than 189 collisions per 100 million VMT. If all those drivers also started texting and watching TV, those freeways would likely begin to resemble war zones.

But autonomous vehicles will be able to pull off such feats. Indeed, their ability to travel at speed with less distance between them can potentially increase freeway capacity by 6 or 8 times.

Any time spent in cars will also be far more productive. 

According to Harvard Medical School, the average American driver spends 101 minutes behind the wheel each day. There are 210 million licensed drivers in the U.S., which suggests that collectively we spend around 5.3 billion hours a year wondering why that minivan in front of us is going so slow and listening to soft-rock hits from the 1970s.