I parsed out the 'conventional' car road load hp curve from the 1996 Honda Dream solar racer graph.
The representative car might be a 1996 Accord Sedan,since this is the bread and butter for car sales.
You can see how exponential/geometric the aerodynamic drag curve is,while the Rolling-Resistance load is linear (up to the tires standing wave velocity).
This yellow area drives home the importance of drag coefficient,if we take the easy way,leaving the frontal area alone.