In order to meet the increasingly stringent demands of fuel efficiency regulations, Mazda is rolling out some new green technologies that will be featured in future cars.  Car and Driver's article is here.  A short summary: We like Mazda’s strategy for the simple reason that stuff like stop/start, energy regen, and diesel engines can be added without greatly affecting the fun-to-drive appeal of the company’s cars, nor will they add huge levels of cost.  Sounds good to me.  

Yes there are 100 different cars out there that can be considered "green."  This is evidence that fuel efficiency has passed way beyond fad stage.  See Yahoo!'s list here, where cars are ranked according to their green rating.