As others have already mentioned, the transmission gearing makes a huge difference. In addition to gears, technology and frontal drag coefficient, peak engine e

As others have already mentioned, the transmission gearing makes a huge difference. In addition to gears, technology and frontal drag coefficient, peak engine efficiency to generate enough HP for steady state cruising speed will also vary. https://www.youtube.com/watch?v=s-aK-GDp2tA https://www.youtube.com/watch?v=s-aK-GDp2tA - this is an exaggerated example of how loading an engine 50% vs 90% can impact real world fuel economy.