The science of aerodynamics has been used for decades to improve automotive performance. Today, a second factor comes into play, though: fuel efficiency. The automobile manufacturers are using every tool they have in their design arsenal to meet the federal CAFÉ (Corporate Average Fuel Economy) standards of today and tomorrow.
The first automobiles were little more than square buggies and carriages with engines. Aerodynamics did not come into play since the vehicles were too slow to be affected by the air resistance. But when vehicles started to go faster it was quickly discovered that a car is using more than half its power just to overcome aerodynamic drag. In the 1930s, Chrysler corporation was the first company to experiment with aerodynamic styling. Today, it is a well-known science.
Slippery Isn’t Always Sleek
Up until now, designers and engineers have mainly concentrated on visible surfaces, giving us cars that are attractive, streamlined delights. However, designs have changed as theories evolved about how best to manage airflow and all its elements. Now other car surfaces have come into play.
Aerodynamics you can’t see
The new focus is under the car.Like an airplane, the underside of an automobile is as important to its passage through the air as the top and sides. The problem in the past has been that customers have not been willing to pay for things like panels that smooth out the underside of a car.With the increased emphasis on fuel efficiency, though, carmakers are spending more on those undercarriage details. The folks at Len Stoler in Ownings Mills, a Maryland-based Porsche dealer, say that Porsche AG, in particular, takes undercarriage aerodynamics especially seriously due to the performance nature of the marque.
It’s all about Cd
Engineers measure how slippery an object is with a variable called coefficient of drag, or Cd. The lower the number the better.A couple of examples will help you understand the scale of Cd measurements. Aordinary brick comes in with a Cd of about 2.0. An ultra-boxy Hummer H1 has 0.70 Cd. Most cars these days have a Cd that ranges between 0.30 and 0.35. The Chevy Volt plug-in hybrid has a Cd of 0.28 and the 2013 Toyota Prius claims a 0.26 Cd.
Expect evolutionary changes
Still, the basic shape of a car or truck is the most important factor in its aerodynamic performance. Don’t expect a great deal of change in that department. Engineers say that you can expect a lot of aerodynamic work of the future taking place under the hood and under the floor pan. Engineers say it is possible to improve gas mileage as much as 10% by making the underside airflow more slippery. Combining engine and transmission improvements with new lightweight materials and improved aerodynamics can go a long way toward helping automakers meet the nation’s new fuel economy goals.