[ceejay]

My guess is existing auto (and other) manufacturers have all but locked up world's supply chain of raw materials necessary to make it feasible to manufacture automobiles at large enough scale.

If I were Google (if they seriously want to consider getting into manufacturing their own products) I would look into starting a chain of junk yards and refineries.

[azernik]

It's just a very capital-intensive business with long turnaround times on new hardware designs. It would take not only a lot of investment, but also a large delay on Google's part to get their own car out the door.

[kpil]

It's also requires a lot of know-how, that takes long time to build up.

Building electrical cars removes some of the difference because the traditional drive train is a large chunk of engineering. (Hint, China can't design good engines yet, so they are buying companies with people that do.)

If I remember correctly ABB patched together a electric drive train technology demo car 20+ years ago including a drive by wire system with electric steering and brakes. They probably mostly did it to show off their high voltage pmm controllers.