According to Rebecca J. Rosen at The Atlantic, our cars won’t be chauffeuring us around anytime soon:
This technology is still at its very early stages and 300,000 miles is not all that big of a sample. According to a “cursory” analysis by Bryant Walker Smith of Stanford Law School, “Google’s cars would need to drive themselves (by themselves) more than 725,000 representative miles without incident for us to say with 99 percent confidence that they crash less frequently than conventional cars. If we look only at fatal crashes, this minimum skyrockets to 300 million miles.” We’re still a long way away from there.