Separating different types of traffic could be a good idea, but there's no free lunch in physics. Higher speeds require more energy, period. Heavier loads requi

Separating different types of traffic could be a good idea, but there's no free lunch in physics. Higher speeds require more energy, period. Heavier loads require more energy, period. Wasting momentum due to curvy roads or traffic is inefficient, but higher speeds don't somehow make up for that.