Because even the most fuel-efficient powertrain is limited by the mass and the aerodynamic efficiency of the vehicle it's moving, Mercedes-Benz created the C-class BlueEfficiency. Debuting at the Geneva Show and headed for European showrooms in the spring, this trio of highly optimized sedans incorporates a load of weight-saving tricks and subtle aero enhancements with the singular goal of cutting fuel consumption.
Weight reduction, compared with the standard versions of the C-class, ranges from 42 to 71 pounds. Savings come primarily from the use of a new lightweight laminated windshield, lighter insulation material, and aerodynamically optimized forged aluminum wheels.
Wind-cheating modifications, including a ride height lowered by 15 millimeters, a smooth belly pan, a variable radiator shutter that manages the amount of air flowing through the grille, resculpted mirror housings, and sealed gaps between the bumper, headlamps, and hood, lower the car's drag coefficient by 7 percent, from an already-fine 0.27 to 0.25. New tires from Michelin lower rolling resistance by 17 percent.
On top of those measures, BlueEfficiency models feature taller final drive ratios and a shifter display that prompts the driver to execute gearchanges to maximize fuel efficiency. Mercedes claims this "ECO Training" program, diligently followed, can help cut fuel consumption by 15 percent.
The BlueEfficiency C200 CDI uses a 134-horsepower 2.2-liter four-cylinder turbodiesel, returning an estimated 46 mpg (5.1 liters of diesel per 100 kilometers), 10.5 percent less than the standard car.
The C180 Kompressor packs a 154-horsepower supercharged 1.6-liter four-cylinder gasoline engine (downsized from the standard C180's 1.8 liters, but retaining the same output figures), to return 36 mpg (6.5 l/100km), 12 percent less.
The C350 CGI (pictured above) uses a 288-horsepower 3.5-liter direct-injection gasoline V-6 to return 28 mpg (8.4 l/100 km), a 10-percent savings.
Photo courtesy of Mercedes-Benz.
