It is worth keeping in mind that even without automatic vehicles, vehicle deaths have and will continue to fall massively.

From the worst in 1937 (29.357 per 100K pop) to today (10.345 per 100K pop), and falling by on average 2%/year since 1996 (was 15.8599 in 1996).

Without trying to sound melodramatic, cars built in the 1990s are "death traps" by 2015 standards (and the same is true of 19980s cars by 1990s standards). The reason we're seeing it fall slowly is as the late 1990s vehicles gradually disappear.

I suspect we'll see a massive drop again in the next ten years even without fully automatic cars as systems like Eyesight auto-break to slow collision speeds.

One thing which will get interesting when we do have completely automatic vehicles is: current drink driving laws (in particular in the US) aren't compatible with them. In many US states falling asleep in a parked vehicle with the keys is enough to get someone for "drink driving" (even without the driving part), so falling asleep in an automatic car could still get someone a DUI.