Green isn't always green - sometimes it's blue. Or at least that's what Mercedes-Benz wants us to think when we think of efficient, environment-friendlier motoring. And to help back up Mercedes' claim to being one of the cleanest luxury carmakers, it has announced it will have 58 BlueEfficiency models on the market by the end of the year, including the new additions to the E-Class range revealed yesterday.

Like BMW's EfficientDynamics tag, the BlueEfficiency name is used to demarcate cars that combine a range of efficiency-enhancing design features and materials to yield a completely conventional car that's nonetheless up to 23% more efficient than a typical vehicle.

"The success of this concept is clearly demonstrated by the new E-Class, which combines state-of-the-art engines and the world's best cd value in this vehicle class with further targeted vehicle optimization measures, including lightweight design and intelligent energy management," said Dr. Thomas Weber, Daimler board member for group research and development for Mercedes-Benz cars.

BlueEfficiency shouldn't be confused with the emissions-enhancing diesel BlueTEC technology, though more of those will be joining the ranks as well. Already the GL, M and R-Class vehicles are on the U.S. market, and will soon be joining the European Mercedes fleet.

The next step forward is the hybrid, however, and the S400 Hybrid claims the title of the most fuel efficient luxury sedan with a gasoline engine at 29.8mpg US (7.9L/100km) in the combined European cycle. Joining it in the lineup is the ML450 Hybrid, itself rated at 21mpg city and 24mpg highway (11.2 and 9.8L/100km, respectively.

These three elements highlight the core aspects of Mercedes' strategy for efficiency: applying technology to the problems of fuel consumption and pollution.

Looking to the future, Mercedes has plans to make advances in electric vehicles and fuel cell technology that promise to completely offload the emissions generation process to electrical energy or hydrogen storage plants, which by their design nature can more efficiently process and treat the harmful by-products of the energy generation process. An early preview of what an electric Mercedes will look like can be found in the shape of the recently announced SLS AMG Electric.