Car-rental giant Hertz Corp. said it planned to offer the Smart fortwo electric vehicle as part of a car-sharing program in three metropolitan areas starting later this month. Hertz will make the tiny vehicle -– a two-seater smaller than a Mini or even the new Fiat 500 that’s about to hit the U.S. auto market -– as part of the Connect by Hertz car-sharing program in New York later this month. It is part of an effort by Hertz to offer a variety of electric and plug-in hybrids worldwide.