The popularity of a sliding side door on the driver's side of the Chrysler minivans caught everyone by surprise. Buyers of Ford's Windstar, the closest competitor to Chrysler's trio of big minivans, have had to make do with a large optional driver's door for rear access from the driver's side. Those days are over. The newest version of the Windstar gets a second sliding door. What's more it's available as a power-operated door. Windstar still rates best in government safety tests and it offers some new features that set it apart from other minivans.