Elon started a company called the Boring Company with the goal of accelerating underground tunneling speed. The hope is to build an underground infrastructure to alleviate the traffic above ground. He spends about 2% of the times on this side project.
The goal for Tesla self driving cars is to take a trip from a parking lot in California to a parking lot in New York without having to touch the wheel by the end of 2017. In fact, Elon believes that we would be able to dynamically change the route say from Seattle to Florida and it would still be able to take you there.
Self-driving cars will never be 100% safe as traveling in a car lends itself to at least some kind of probability that it will crash. But if autonomous driving can get to something like it is unlikely to crash in a hundred lifetimes or a thousand lifetimes, people may be okay with that.
Elon is working on a Tesla semi-truck and has already test driven it on a track. He was impressed with the nimbleness of the vehicle given the size of it. It is said to have enough torque to pull a diesel or gas truck up a hill.
One gear Tesla semi-truck will have more torque than any diesel or gas powered truck
Solar glass roofing will be less than the cost of the roof plus the cost of electricity. Therefore economically it will be a no brainer. Supposedly even when the house is long gone, the glass will still be there.
Solar glass panels will cost less than regular roof + electricity
The Gigafactory is producing lithium ion batteries already and eventually it will get to a production level of hundred gigawatt hours of batteries a year. When fully completed the Gigafactory will be the shape of a diamond.
Space X had a reflight of an orbital booster making it the first to accomplish this feat. Elon has the idea of sending people to Mars. Supposedly the rocket would have a thrust equivalent of 120 747s with all engines blazing. The rocket would be able to take a 747 with maximum fuel and maximum passengers and cargo as its cargo.
Space X rocket to Mars vs a human (small speck to the right of the rocket)
On why Elon is doing all of this.."I think it is importing to have a future that is inspiring and appealing. There ought to be reasons you get up in the morning and want to live. Why do you want to live? What is the point? What inspires you? What do you like about the future?"
As humans use up our finite resources, the world will move towards utilizing and creating sustainable energy. That Elon believes is inevitable, but he wants to accelerate it even if it is by a decade or whatever.
Technology doesn't happen automatically. It takes effort to improve it. By itself it will degrade. For example in 1969 we sent someone to the moon and the space shuttle went into orbit. Then for a time nobody was going into orbit. Take for example Ancient Egypt and the pyramids or the Romans and the aqueducts. They stopped innovating.