[oldbeaver]

Yes, one can write a sketch, take measures and make an estimation.

Anyway, there is some links to tables at the bottom of the page, where there is the table. I tried it up with some precise measures and some very approximated others, and the results are VERY illustrative.

At 120 miles/h my car spend 47 HP of which about 40 are to overcome air resistance and only 7 correspond to rolling resistance. The table shows progression over all speeds.

Now I understand why people devote so much effort to aero mods. Even the manufacturers spend a lot on design to producing better aero cars.

Again, one of the most interesting and valuable contribution to the subject.

Thank you very much !