I think an argument can be made that a moving vehicle is no different than a lethal weapon, and the autopilot, nothing more than a safety mechanism on said weapon. Which is to say the person in the driver's seat is responsible for the safe operation of that device at all times, in all but the most compromised of circumstances (e.g. unconscious, heart attack, taken hostage, etc.).
Ruling otherwise would open up a transportation hellscape where violent acts are simply passed off to insurance and manufacturer as a bill. No doubt those parties would rush to close that window, but it would be open for a time.
Cynically, a corrupt government in bed with big monied interests would never allow the common man to have this much power to commit violence. Especially at their expense, fiscal or otherwise.
So just or unjust, I think we can expect the gavel to swing in favor of pushing all liability to the driver.