There's a lot of competition to be seen as the world's greenest automaker – just look at the branding efforts surrounding the Toyota Prius or the Chevrolet Volt for examples – but if you look at the way an automaker designs, builds and recycles its products, then BMW is the top dog.At least that's the case if you're consulting the Dow Jones Sustainability Index World, which has declared BMW Group to be the "most sustainable automobile company worldwide."...