Fiat Chrysler Automobiles NV is laying out a vision of a battery-powered, self-driving minivan that it bets even a millennial could love. That may not be enough to shake the automaker’s image as the purveyor of the least fuel-efficient fleet in the U.S. The automaker’s fifth-generation minivan, whose design concept is called the Chrysler Portal, would have a 250-mile electric range and enough screens, ports and social-media options to entertain young families while software handles much of the driving.