Protect the passenger at all costs or minimize the number of casualties? What ethics for autonomous vehicles?

The introduction of driverless cars (henceforth called AVs) promises to improve traffic flows, reduce pollution and eliminate up to 90% of road accidents. What is slowing down the marketing of AVs is not their technical profile, but rather the difficulty of defining the “moral” algorithms that will guide such vehicles in situations of unavoidable harm. Bonnefon, Shariff and Rahwan found that partecipants in six Amazon Mechanical Turk studiues approved of utilitarian AVs that sacrifice their passengers for the greater good, but they would themseves prefer to use in AVs that protect the passenger at all costs. The question is: What ethics for autonomous vehicles?