Just played around the tool and it would be super sweet if you could add multiple engine efficiency numbers based on speed. You can "easily" calculate those from BSFC maps. Then the calculations would be more accurate at wider range of speeds.
Now in this calculation I know I will get 3 liters at 62 MPH with actual 36% efficiency speed but its off 40 MPH speed. I know the efficiency at 40 MPH in my car will be about 33%. That aint big difference but if you use that 5-200 MPH calculation there start to be some real differences in engine efficiency. I can calculate multiple points and make my own chart but maybe it would be easier if the program would do it automatically if you add your engine efficiency point there?
Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com