Your Car’s Aerodynamics and Fuel Efficiency: The Details That Decrease Drag

aerodynamics and fuel efficiencyIn their continuing efforts to improve the fuel mileage of their fleets, auto manufacturers are placing a renewed emphasis on aerodynamics and fuel efficiency.

A moving car must expend energy to plow through the air that surrounds it. The faster you travel, the more impact these forces have on your car; at highway speeds, more than half of the fuel being consumed goes toward overcoming wind resistance.

Coefficient of drag

The amount of wind resistance created by a car is measured as its coefficient of drag, or Cd. The lower the coefficient of drag, the better the car’s aerodynamics and fuel efficiency will be. Most passenger vehicles on the road today have a Cd between 0.30 and 0.45, although more and more cars — including many hybrids — are starting to sport ratings below 0.30. Since a minuscule 0.01 decrease in Cd can easily give you an additional 0.2 mpg, car manufacturers are constantly looking for ways to reduce drag.

Improving aerodynamics

Besides the obvious sleeker profiles of today’s cars, there are many less noticeable ways that car designers can and have improved aerodynamics and fuel efficiency.

  • Undercarriage improvements – Look underneath most cars and you’ll see a collection of pipes and shafts that are clearly not aerodynamic at all. Smoothing out the undercarriage is one of the biggest and least visible ways to improve aerodynamics and fuel efficiency.
  • Fins – Some vehicles, and in particular the newest Lexus models, incorporate tiny fins or ridges to the lights, mirrors and undercarriage of the car. These barely-noticeable fins adjust the airflow around the car to reduce drag and improve stability.
  • Grilles – The grille of a car is designed to catch air in order to cool the radiator and engine. Some manufacturers are working on more aerodynamic grilles that partially close at highway speeds, when less air intake is needed.
  • Seams – Reducing or eliminating gaps between body panels or between the hood and the car help cut down on wind resistance.

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