[aerohead]

Originally Posted by CapriRacer

The above was from this book:

Tires and Passenger Vehicle Fuel Economy



It would seem that aero not as big a contributor as some might think.

I'm going to guess that the values shown,are for only for the EPA Mobile Sources dynamometer testing protocol.(which includes stops,idling,accelerations,decelerations).
*Real world,steady-state,highway cruising can demonstrate 36% thermal efficiency at the flywheel for an ICE.(higher for diesel).
*Powertrain losses are only 4% (under power) for a non-overdrive,manual transmission.
*Of the 'available' tractive power,on the highway,at 100 km/h,aerodynamic demands can constitute 80% of the overall road load.
*With rolling resistance absorbing the remaining 20%.
For decades I've considered the (b) table to be extremely intellectually dishonest.Almost conspiratorial in downplaying the significance to aerodynamic drag at highway velocity.