Improve Your Fuel Economy by Learning to Drive and Modifying Aerodynamics

By PSU EcoMerge Capstone - 5:33 AM

Aerodynamic Drag – The force on an object that resists its motion through a fluid is called drag. When the fluid is a gas like air, it is called aerodynamic drag (or air resistance).

How to Measure the Drag on a Car?

3 factors determine a vehicle's drag: 1) its speed, 2) the cross-sectional area it presents to the wind, and 3) its drag coefficient or Cd. The drag coefficient is a measure of the "overall slipperiness" of a vehicles shape.
Go Visit, and learn 4 steps of how to measure the drag coefficient of your car.

So, what are all the ways to cut drag down? Since aerodynamic pressure creates resistance to forward movement, did you know that drag increases as the square of speed? Double your speed from 30mph to 60mph QUADRUPLES your drag! Therefore, slower speeds help and anything that cuts down resistance helps.

Sources of Aerodynamic Drag in Automobiles and Possible Solutions

2 biggest things you can do to improve your fuel economy are learn to drive and modify your aerodynamics. Drag reduction takes a back seat to driving techniques, but no one is saying you can't do both! This will serve as an overview of basic sources of drag and the modifications that people go through to try and cut their Coefficient of Drag to more fuel economy-friendly levels.
General Shape
The shape of the car is the most important thing to aerodynamics. Although you can't do much about your existing car, you can consider aerodynamics when purchasing your car. Also, if you're up for it, there is one thing. This modification is called a boat tail. One of the main principles in aerodynamic body shape is that a smooth, long, tapered surface should be attempted in order to keep attached flow through the end of the car. But, at the end flow is generally cut off abruptly, which is where a boat tail, a short extension of the end of the car, adds a greater length over which flow may taper.

Mirrors contribute a huge amount to the aerodynamic drag of a car, especially for how small they are. There are several solutions to this problem. One such solution is to install smaller mirrors that won't create such a large amount of frontal area and turbulence. Another solution is to install folding mirrors and fold the mirrors back when you reach highway speeds. Also, you could just eliminate the passenger mirror, or both, using head turns to check before making lanes changes and performing other maneuvers. Many Insight drivers have eliminated their mirrors and replaced them with cameras so that they could still get an optimal vantage point without turning their heads.

The underbody is another big source of drag on most vehicles. Most underbodies are designed without care for aerodynamics, which is good and bad. Bad is because most of us are starting off with terrible underbodies; good because there is a great improvement in Cd to be had from a full under tray. Some cars, such as the Acura NSX come with full under trays, but for the rest of us, "The contribution can be up to 25% of the total drag. Careful design can achieve a change in Cd of -0.02 on serial production cars."

Particularly because of the shape and design of the radiator it causes a large amount of aerodynamic drag. Radiators are designed for worse case scenarios, scenarios most of us are never likely to be in, which is why a grill/radiator block can easily and safely be installed on most cars. If you're considering modifying your car for improved aerodynamics and fuel economy, this is the first place for you to start!

Surprising, tires cause a large amount of aerodynamic drag. This drag can be reduced by moving to a slimmer tire and reducing area in the wheel well where turbulent flow can exist. Besides, wheel covers are a stylish and cool way to modify your tires for fuel economy. Lacking a picture of some mounted on a car at the moment, check out this set on the right to see what you're getting yourself into: They do work and your brakes will still cool themselves properly, so don't worry about safety with these things.

The rear wiper on the CRX makes a .01 difference in Cd. Consider removing it and treating your rear window with a product such as Rain-X. Some people eliminate one of both of their front wipers and rely on glass treatments, and some remove the blades and keep them in the trunk, so that if it does rain they can simply pull over and pop them back on!

The radio antenna rounds of the rest of the serious drag contributions, and the only way is to remove it!

Vehicle Speed Surveys

It provides greater detail and accuracy and suggests a dramatic increase in excessive speeds on roads. As vehicles travel faster, the energy required to overcome aerodynamic drag increases approximately exponentially, and becomes the dominant term in total fuel use. The ERR transport Emissions Model was used to calculate the additional energy consumed, and the potential savings from enforcing or reducing speed limits. The results suggest that 3.1% of car CO sub (2) emissions (0.6 Mt C) could be saved if current speed limits were enforced, or 7% (1.4 Mt C) if a maximum limit of 50 mph were imposed.

The Video about Reducing Aerodynamic Drag

Reducing a vehicle's aerodynamic drag can improve a car's fuel economy, say automakers. Not only can designers make it easier for a car to push through the air, automakers report drivers can also pull their weight by removing unused bike, ski or luggage racks off the vehicle's roof. An extra 100 pounds can reduce your MPG by 2%.

The video includes general views of the Chevrolet Volt and other aerodynamically designed cars, SoundBits on improving fuel economy and an edited package on how to save on gas by reducing a car's wind resistance.

A Call to Action…
  1. Slow down
  2. Modify your mirrors
  3. Look into the grill/radiator blocks

It is we human beings’ duty to save fuel. After reading the post, we must take actions and act on effective fuel-saving activities by improving our own cars in environment-friendly ways. The urgency of this task has become undeniable.

This “Call to Action” represents the next step. It is intended to be the potential enforcement. Therefore, it details sources of aerodynamic drag in automobiles and the possible Solutions. Many solutions will require an initial investment but, over time, will vastly decrease drag, improve fuel economy, and ultimately let our earth walk on a more sustainable path.

Aerodynamic drag is unavoidable but can be minimized, so the solutions mentioned above are deserved to invest. The intention of this “Call to Action” is to encourage constructive input by automakers, car-owners, drivers, and any related stakeholders, that move us forward.

Human Beings who care deeply about fuel-saving, our fuel economy, and environment must all take up the fight together for comprehensive improving activities, and aerodynamic modifications are the most important modifications you can make to your car. I believe — very strongly — that everyone has an obligation to do it, and I believe that we human beings cannot postpone any longer.

With a “must do” spirit and take the solutions seriously and you can have a good looking car with greatly improved gas mileage and fuel economy, and your car will save the only planet.

Posted by YiChen Chen

Fergusson, M. (1994). The effect of vehicle speeds on emissions. Energy Policy, 22(2), 103-106. Retrieved from

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