[ACEL]

I read somewhere :

“The Effect of Aerodynamic Drag on Fuel Economy”
Aerodynamic drag is proportional to the square of velocity, and hence the power needed to overcome drag is proportional to the cube of velocity.
if you make a 10% reduction in aerodynamic drag your highway fuel economy will improve by approximately 5%, and your city fuel economy by approximately 2%.

If I take this upside-down, it would read like:

If your highway fuel economy improves by 5%, that is because you made a modification that brought a 10% reduction in aerodynamic drag.

So that means sort of one can compute the drag coefficient inferring from the fuel economy improvement like you get a percentage in drag reduction that is double to the percentage in fuel economy.

So if I go creasy about this hypothesis:

Right now, I get 27,3% fuel economy over EPA, then did I get a 54,6% reduction in Cd? From the original 1999 Acura EL Cd=0,34 or Cd=0,32, the actual Cd would be around 0,15? That seems very optimistic.

I revised the data, mod by mod, and the results are in the attached pic file. The drag reduction computed would rather be 36% in average in the speed range of 116-125 km/h for an actual Cd in the range of 0,20-0,22.

Boy, it seems that car had an aerodynamics improvement potential from the start. There are some other mods I want to try, before I am done:

- Front wheel air curtains,
- Front wheel "aero-corners" - separation edges,
- Reduce front wheel arches,
- Rear wheel skirts

With some luck and budget, I will go back to the mechanical side of the Force and replace the 195-55R15 tires by some 195-65R15 with will allow to go from about 2700 RPM at 100 km/h to 2550 RPM. Then, to improve the exhaust flow, I may replace the catalytic converter and muffler. I do not want a noisier car but a better breathing engine, better torque and better fuel economy.

After all, a better fuel economy, a quieter car that looks good is all that I work for.