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Flat route to maximize efficency

5128 Views 6 Replies 7 Participants Last post by  deeks
Maybe put his under the gamification of driving. What are your thoughts choosing a route based on elevation change and slope? I watched a Top Gear episode a few years ago where they debated what was best for fuel efficiency - flat or 'what goes up must come down'. I found a website,, that maps a trip and has elevation and slope but you have to do some calcs to get totals.

My guess is that it is a wash due to commutative law [minus system efficiencies] but wonder if anyone played around with this as part of driving strategies. I have a trip in a few weeks over the continental divide and choosing a route.

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As soon at you touch the brakes, use engine braking, or regen, you become less efficient. Or if the downhill exceeds the target speed, that burns energy as well since speed increases are not proportional when it comes to energy lost.

So for gentle rises, not a big deal. For steep grades, you take a big hit.

Another item is cross wind. People assume that if you a roundtrip with a crosswind, you don't lose anything. But, it effectively increases the frontal area and increases the CD too.

Head winds and tail winds also hurt a roundtrip. Say your target is 65mph and the wind is 5 mph. Going with the wind gives you a drag equal to 60mph. Going into the wind gives you 70mph. The difference in drag from 65 to 60 is less than the drag difference from 65 to 70. The higher the windspeed, the more the effect.
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