Modifying a Ford Mustang for maximum efficiency & performance.

I started this fuel economy project after Ford released 2011 Mustang. 305 HP, and 31 mpg highway with the automatic. I knew with a standard transmission, I could modify it to perform better than highway in the city. The gear heads dream- 40 mpg city with 5 second 0-60 times on a Front Engine, Rear wheel drive (FR) car.


  • Background – the car & driving influences
  • Research & construction
  • What fuel economy does it get?
  • What’s it like to drive?
  • Compared to “regular” cars…
  • Aero observations: bugs, leaves & deer
  • The aerodynamic modifications in detail
  • Cost

Update: January, 2014 – $1579.99 in Savings

As of January 2014, my improved mileage has saved me $1579.99 in gasoline over what it would have cost me to travel the 27,000 miles at my original mileage (pre-modified). This is over an 17 period. Not a bad return for the investment in aeromods.

Background – the Car & Driving Influences

My car is a 2012 Mustang which I bought new, has an EPA fuel consumption rating of 19 mpg (US) city / 29 highway, and averaged high teens’s when driven by a “normal” Mustang owner.

Since I had started driving, I had been using hypermiling techniques to get me up to an average in the low 30’s, but I had to keep the speed below 60 mph (95 km/h) to achieve it, which can be inconvenient to do on busy highways. In college with a decaying car, I stumbled upon a website that quantified my driving technique, and took it a step further-¬†using commonplace materials from the local hardware store to lower the drag coefficient (Cd) and improve its gas mileage at highway speeds, and even in the city.

Research & Construction

My inspiration was a 1930’s German car which was a streamlined 1939 Maybach designed for The Fulda Tire Company for high speed tire testing on the autobahn and could cruise at over 150 mph with a 150 hp engine. I also researched some of the more recent low Cd concept cars that used recently developed aerodynamic techniques to clean up the airflow around the wheels.

I built the aero mods in aluminum bar, Coroplast, and even at times cardboard. Since I was building this car for use as a commuter, not a show car, or as a “no holds barred” extreme high mileage vehicle, everything I did to the car had to pay for itself in fuel savings within two year’s time-and look decent.

The end result is a car with such low aerodynamic drag that it is below Prius territory.

What Fuel Economy Does it Get?

The approximate mileage on a level road burning 10%-ethanol gasoline at 85 degrees F ambient (29.4 degrees C) is:

  • 56.50 mpg (US) at 44 mph
    (4.16 L/100 km at 105 km/h … 24.02 km/L … 6785 mpg (Imp.))
  • 49.65 mpg (US) at 54 mph
    (4.73 L/100 km at 113 km/h … 21.10 km/L … 59.62 mpg (Imp.))
  • 41.45 mpg (US) at 64 mph
    (5.67 L/100 km at 129 km/h … 17.62 km/L … 49.77 mpg (Imp.))
  • 38.6 mpg (US) at 74 mph
    (6.09 L/100 km at 145 km/h … 16.41 km/L … 46.35 mpg (Imp.))

Using fuel WITHOUT ethanol raises these numbers by about 3 mpg, but side by side testing is impossible and done year over year.

What’s it Like to Drive?

I have to get above 60 mph before I start to feel any wind load and it has a calculated top speed of about 185 mph with its 305 hp engine (the OEM max speed was 113 mph). The wind load I now have at 60 mph is close to what I used to have at 50 mph. Wind noise is practically non-existent compared to it’s form before modifications. It’s a joy to drive on the highway since it doesn’t feel any wind load at normal highway speeds and loses speed MUCH more gradually than a normal car when coasting.

Compared to a “normal” car…

This car coasts so well that when I switch from driving this car to a “normal” car, it feels as if I am driving on a road covered with molasses, and that, like a powerboat, you have to keep pouring on the power to maintain headway. By contrast, with this car on a level road it only takes a light touch on the accelerator to maintain speed and it takes only the slightests of downhills to maintain speed in a coast. Even a Prius now feels “draggy” at highway speeds compared to this car.

Needless to say, the car doesn’t get much attention on the road with all modifications equipped being hidden, or blending so well. Some think it is sacrilege to do this to a Mustang, but power AND efficiency can’t be beat.

Aero observations: bugs & leaves

A fringe benefit of the aeromods are that the bugs in the summer and salt spray in the winter pass over my car without impacting much- or leaving interesting designs. So I don’t have to clean dried bugs or road salt from my windshield and rarely need to wash the car to remove the dirt and salt that accumulate on the usual surfaces of most cars, with the exception of the front bumper and the rear end of the car. It is interesting to see the salt patterns from the wheel wells, and how the air flows around the car.

When driving through snow, the snow flakes ahead of the car smoothly lift, and simply pass over the top of the car. The air also moves smoothly under the car so leaves and other debris on the road move only slightly as I pass over them.


So now, for a total materials cost of $200, I’ve created a car that blows away the highway mileage of any car currently in production with 2/3rds the power. I wish I could buy a car with as low drag as this one, and even though the car companies are starting to come out with higher mileage models, they still have a ways to go match the low drag and highway mileage of mine. You can buy a fun car AND get good mileage. Why restrict mileage to a weak front wheel drive or hybrid?

Be rewarded the Web's Premiere Rewards Site