Modifying a Honda Civic for maximum MPG
I started this project after the Hurricane Katrina-inspired gas price run up, as I have a long commute and, except for a few hybrids, the car companies were busy introducing models with ever poorer gas mileage.
Overview:
* Background - the car & aero influences
* Research & construction
* Coastdown testing to calculate Cd
* Update: lean burn engine installed for more MPG
* 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
* Aerocivic media coverage & links
* Other aeromodded vehicles
Background - the car & aero influences
My car is a 1992 Honda Civic CX which I bought new, has an EPA fuel consumption rating of 47 mpg (US) highway / 39 city (5.0/6.0 L/100 km ... 20.0/16.6 km/L ... 56.4/46.8 mpg (Imp.)), and averaged mid 40's when driven "normally".
Before Katrina, I had been using hypermiling techniques to get me up to an average in the high 50's, but I had to keep the speed below 55 mph (89 km/h) to achieve it, which can be inconvenient to do on busy highways. About this time I had read Phil Knox's article "Free Fuel Riding on the Wind" in EV World where he talked about using commonplace materials from the local hardware store to lower his truck's drag coefficient (Cd) and improve its gas mileage at highway speeds. Also, having lived in Germany, I was familiar with many of the ultra-low Cd cars designed in Germany during the 1930's.
Since it didn't look like the car companies were planning to do anything in the foreseeable future about introducing a small car that would get good fuel economy on the highway, I decided to see what I could do towards improving my existing car's gas mileage.
Research & construction
1930's aerodynamic test car First, I studied the 1930's German cars and found one whose shape roughly matched my own car's. This car 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.
Initially I built the aero mods in aluminum bar, Coroplast, and clear vinyl and then as they proved themselves, rebuilt them in the stronger and more permanent aluminum monocoque and Lexan, using construction techniques common on homebuilt aircraft. 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. Since it was a 15 year old car with over 350,000 miles (563,270 km) on the odometer at the time that I started this project, I had no concerns with resale values.
The end result is a car with such low aerodynamic drag that it is down in concept car territory and well below the 0.25 Cd (coefficient of drag) of a Toyota Prius (3rd generation).
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