[kach22i]

Apr 09, 2013
Slippery Slope: Production Cars Making Jaw-Dropping Aerodynamic Gains
A new trend sweeping the industry is aerodynamic vehicles that look fashionable, rather than like science projects.
https://www.wardsauto.com/technology...odynamic-gains

While not quite as slippery as the XL1, the CLA is part of a new trend sweeping the industry: Aerodynamic vehicles that look fashionable, rather than like science projects. In addition to the Mercedes, mainstream models including the Chevrolet Malibu and Toyota Avalon are sporting shockingly low Cds without looking like Sci-Fi props.

Teardrop-shaped bodies, fender skirts and other typical aero gimmicks may work miracles in the wind tunnel, but when they hit the street, consumers reject them. GM’s EV1 and first-generation Honda Insight HEV were the most aerodynamic vehicles of their day, sporting Cds of 0.19 and 0.25, respectively, more than 10 years ago. Despite innovative design and breathtaking efficiency, both flopped.

There are many reasons why the cars failed, but nerdy fender skirts and pinched hindquarters did not help...............

The CLA achieves much of its slipperiness like most new vehicles: Designers carefully manage how air streams around the car’s A-pillars and side mirrors, and how it flows through the engine compartment and around the wheels. Special underbody panels allow air to pass more freely underneath.

However, the CLA180 BlueEfficiency model achieves a world-leading 0.22 Cd with an additional list of features, including a sport chassis and suspension for a lower ride height; smaller 15-in. wheels made of a light alloy and designed to be highly aerodynamic; a radiator partially covered by a blind for active regulation of cooling air and additional belly pan and under floor treatments.

These efforts are topped off by a special rear bumper that hides the exhaust pipes and plays a significant role in lowering aerodynamic drag, a Mercedes spokesman says.............

Even so, 60% of drag still is related to the upper body of the vehicle, and tapering the roofline and rear end is on the mind of every auto maker in an effort to reduce a vehicle’s wake area. Because this can negatively impact rear-seat hip space and luggage volume, as well as aesthetics, designers are proceeding cautiously.