This one has me puzzled. Automakers seem to use "Blue" to refer to eco stuff when it comes to our cars. For example, my VW Golf R (not exactly an eco-wagon) has a "Blue Trainer" which teaches you how to drive economically, they use "Think Blue™" in their marketing, and have BlueMotion badged cars that are more fuel efficient and emit fewer nasties. Similarly, Mercedes use BlueTEC on their diesels for the same purpose. I guess Blue would make sense with hybrid/electric vehicles, but mine is definitely not that!
Why "Blue"? Why not "Green" or "Eco"? Is there some strict definition for Green or Eco? A trademark?