Mercedes-Benz CLA180 cheats the wind

Mercedes-Benz claims its new CLA180 BlueEfficiency Edition will be the world's most aerodynamically efficient production road car when the European deliveries begin in June.

The swoopy four-door sedan forms part of an initial five-car lineup of CLA models set for a public debut at the Geneva motor show in March.

With an official drag co-efficient of 0.22, the CLA180 Blue Efficiency Edition undercuts the existing aerodynamic champion, the Mercedes B180 BlueEfficiency with the optional eco technology package, which claims a 0.24 Cd.

By comparison, the Toyota Prius is rated at 0.25 Cd and the BMW 320d EfficientDynamics at 0.26 Cd.

The key to the CLA180 BlueEfficiency Edition's wind-cheating prowess is its relatively small frontal area of 23.8 square feet (2.21 square meters) and a series of subtle refinements not found on other CLA models.

The refinements include a reworked front apron, improved sealing for the headlamp surrounds, altered airflow guidance to the radiator, an adjustable radiator shutter, serrated spoilers to guide air into the wheelhouses, front wheelhouses with integrated spoilers and slits to reduce pressure buildup, new mirror housings, aerodynamically optimized wheels and tires, extensive underbody cladding, a redesigned exhaust and refinements within the rear edge of the roof.

The CLA180 BlueEfficiency Edition is powered by a 1.6-liter four-cylinder direct-injection gasoline engine developed with Renault. With 120 hp and 147 lb-ft of torque, it pushes the car from 0 to 62 mph in 9.9 seconds. A six-speed manual is standard. Top speed is electronically limited to 118 mph.

Combined fuel economy for the CLA180 BlueEfficiency Edition is put at 47.0 mpg on the European test procedure, which typically results in higher fuel economy numbers than the U.S. test. By comparison, the standard CLA180 is rated at 43.6 mpg on the European test.

Meanwhile, Mercedes-Benz is planning to extend its leadership in road car aerodynamics with the opening of a new wind tunnel at its Sindelfingen research and development facility near Stuttgart, Germany.

Set to go into operation by this summer, the new facility includes a rolling road as part of a 62.3-foot-long floor area and is capable of providing measurements at speeds up to 165 mph. The fan used to provide wind resistance measures 29.5 feet in diameter, uses 18 blades, provides a maximum volume of wind of over 7,063 cubic feet and powered by an electrical motor producing 148,991 lb-ft of torque.

Until now, Mercedes-Benz has relied heavily on the University of Stuttgart and its own original wind tunnel located at its nearby Untertuerkheim manufacturing base, which celebrated its 70th anniversary earlier this week, for much of its aerodynamic work. When the new wind tunnel begins operations in June, Mercedes-Benz plans to begin updates at its Untertuerkheim facility.

By Greg Kable