Terrain and road surface affect fuel economy

One of the things we learned during Run on Less, the fuel economy road show, was that many factors play a role in fuel economy.

We looked at things like weather, temperature and elevation during the three weeks of the Run. I did an earlier blog on the impact of winds as the Run took place during both hurricane Harvey and hurricane Irma.

One of the areas we plan to explore more deeply in our full report on the Run, which we plan to have out this spring, is how elevation effects fuel economy. We know that traveling on a downhill grade improves fuel economy and in hilly country helps to counteract the losses in fuel economy sustained by traveling upgrade and that the power needed to move a vehicle increases based on steepness of the grade.

But that is pretty general and we want to provide some hard data that more specifically addresses the fuel economy gains and losses from elevation changes.

In addition to hilliness or flatness of the road the road surface itself can cause significant differences in fuel efficiency.

And while we did not specifically track this during the Run, we know that type of road surface can affect tire rolling resistance. And rolling resistance has a significant impact on fuel economy.

Smooth-textured highway surfaces provide the lowest rolling resistance, while coarse-textured surfaces give the highest tire rolling resistance and the lowest fuel economy.

Studies have shown that road roughness can increase rolling resistance up to 20% due to energy dissipation in the tires and suspension.

While you can't change the surface of the roads you travel nor change the elevation, it is important to include these factors in your analysis of your fleet’s fuel economy.