To continue your example, I'll pose that any system with unilateral behavior of self-endangerment is extremely problematic. Motivating example: assume that self-driving cars will always avoid head-on collisions with other vehicles, even if there's no safe alternative. Including driving off a cliff. Attack: manual driver drives down the wrong side of the road (or maybe the middle of a two-lane road), forcing all of the self-driving cars off the cliff during evening commute hours to a hillside residential neighborhood. I suspect all systems that don't hew to some baseline of self-preservation are subject to similar modes of attack.

I might also have heard about some of these problems from Brad Templeton, who describes "Abusing robocar collision-avoidance" among many other interesting problems at

http://www.templetons.com/brad/robocars/downsides.html

I don't remember if he also mentioned the kidnapping scenario when I heard him present about this.

What alternative would a human take? Would they kill the kidnappers by driving over them?

These scenarios are kind of vague because they don't make it clear whether the self-driving car lets a human driver take over and take full responsibility.

Of course, in many countries that would count as self defense (if kidnappers were armed and pointed guns towards your car).

Neiter of those. The first and foremost rule in traffic is to act predicatable. And the only predictable reaction to something blocking your way is to BREAK!

Seriously, what is it always with people that makes them think that a change in direction (swerving) was a good collision avoidcance strategy?

Newsflash, it's not! When swerving you don't change your momentum, you just redirect it (apart from friction losses, of course, the the teensy bit of angular momentum transferred to the planet). More importantly, swerving combined with braking may cause loss of control, which is where there are Anti Break-lock Systems. But ABS will increase your stopping distance, so modern ABS will kick only if the steering wheel does not point into the forward direction.

Of all the scenarios thrown at self driving cars ethics, none of them is an issue if basic traffic rules are followed. And the first and foremost one is, that you always keep so much distance in front of you, that you can come to a full stop within that distance by breaking. And the other first and foremost rule is you never drive faster than road conditions, and more important visibility allow. TL;DR: Don't speed and Don't tailgate!

Any suddenly appearing obstacle in a vehicles way poses the same problem for a human or a computer driver. The computer driver may have the shorter reaction time, but physics is physics and the best course of action remains the same: Braking!

But I agree as a general rule. A lot of this trolley problem stuff is way overblown. Far and away the best action in the vast majority of cases is going to be to slam on the brakes. Even if someone or something still collides, the energy is going to be reduced and therefore the consequences of the collision.

I certainly don't want my car flying off the pavement to avoid hitting something on the road without a really good model of why that's a safer approach for me.

What kind of ethical dilemma should it have on that example?