[NeilBlanchard]

The weight of the vehicle is the only thing that matters for the rolling resistance (if the tires are the same) - it doesn't matter whether it has 2 wheels, or 3 or 4. The weight is divided by the number of wheels, and the rolling resistance total is still the same, if the weight is the same.

Narrower wheels only necessarily affects the aerodynamics. In other words, a narrower tire is not inherently lower rolling resistance.

Trikes can be well done or poorly done - that goes without saying. The point is whether only reducing weight, but not improving aero drag is worth it - if you also sacrifice stability.

I'll point to Allert Jacob's streamliner motorcycle. It now weighs 231 pounds - about 80 pounds more than stock; which is a 34% increase! But, along with taller gearing, the drastically reduced aero drag more than doubled the FE.

Also, the efficiency of the drive train is huge factor. The Edison2 VLC X-Prize car got 102MPGe with an ICE in a 830 pound car. But the eVLC gets 245MPGe with an electric motor despite weighing 1,140 pounds; which is a 37% increase.

Somehow I doubt that the motorcycle engine is as efficient as the original CR-X engine was.

My hypothesis is that drivetrain efficiency is the most important factor, followed by aerodynamic drag, followed by weight, and the fourth most important factor is overall rolling resistance.