Your statistic (vehicle miles versus passenger miles) is probably more relevant, but now I'm curious whether the passenger miles of driverless vehicles are more

Your statistic (vehicle miles versus passenger miles) is probably more relevant, but now I'm curious whether the passenger miles of driverless vehicles are more or less than the vehicle miles, in aggregate. (Although maybe passenger miles is the correct metric -- a driverless, passengerless vehicle could hypothetically plow into an overpass at a speed that would result in a fatality, if anyone were inside; since the passengers of a vehicle are a large chunk of the people who die if that vehicle has an accident, should we car how many people don't die when vehicles are empty?)