Despite their popularity with motorists, SUV’s have been less than a hit with many environmentalists.  But this may change, experts say, as new hybrid technology is helping improve the fuel efficiency of these much-maligned vehicles.  According to Newsday, hybrid powertrains, which combine gasoline engines with small electric motors, are now driving their way into the world of SUV’s and trucks – with the major automakers set to unveil some 18 hybrid powered vehicles in American showrooms over the next four years.  The new Chevy Silverado, for example, will get 12 percent better fuel economy, while the Ford Escape will get a hefty 40 miles per gallon in city driving.  Such achievements may yet throttle anti-SUV hype.