2010 Mercedes-Benz E-Class Coupe - Click above for a hi-res gallery

In a previous post from our Greenlings series, we took a brief look at how and why aerodynamics play a significant role in a vehicle's overall efficiency. To put it plainly, the easier a car is to push through the wind, the better its fuel efficiency is likely to be. Mercedes-Benz has made great strides in overall vehicle aerodynamics with its E-Class Coupe, which boasts an impressive .24 coefficient of drag. According to that car's project manager, Rainer Tiefenbacher, the best is yet to come:

There is still plenty more to come as we explore ways of improving fuel efficiency. Designers are still learning about what works aerodynamically and are having to consider it more and more when they think about how a car will look. There are big steps to be made, especially around and under the engine hood.

Just how low could they go? Very low indeed, it would seem - the German automaker believes it will be selling cars with a Cd of less than .20 in just 5 years.