Curious about electric cars? On your next vacation, give one a test drive—and instead of paying high gas prices, charge up for free. Major car rental companies, which have been offering hybrid vehicles for years, are now getting into the electric car (EV) market. And an ever-growing number of hotels, resorts, and even B&Bs are adding free electric-car charging stations to entice guests to get off the grid and plug in their cars when they travel.