I don't quite agree with the approach here. To me an engineer tries to prevent problems. Period. Ethical decisions and other such concepts can be made obsolete if you prevent problems from happening in the first place.
How to prevent problems? A real engineer (as I see it) always goes closer and closer to the source of the problem. If suddenly a kid appears on the road, how can we detect the kid earlier? If there's a hole on the road, how can we detect it earlier? Always go for extending and improving the sensors of the car so that we detect any relevant variables very early and prevent potential problems.
Can we get to zero accidents? Not in the near future. But if we can get to ridiculously small chances of having an accident on the road, well, that's a huge progress on solving the problem.
Machines have certain advantages over people. They never get tired, their sensors can be extended, they can be made faster... there's really no limit. Let's use those advantages.