Compass Mileage

[Old jack]

New owner of Thor Compass. Interested in speed for best economy.

[16ACE27]

45 mph

[DavidEM]

As 16ACE27 notes above, driving in the mid 40s usually provides the best fuel economy as it is a compromise among speed, increasing aerodynamic drag and operating the engine at its most efficient point.

But nobody drives at that speed, at least not on Interstates or 60+ mph roads.

So here are my tips for best fuel economy:

1. Don't use cruise control particularly on hilly roads. It maintains speed on the way up hill which uses lots of energy and fuel and backs off of the throttle on the way down which helps but never catches up all of the way.

2. On the way up the hill let the speed fall off, maybe as much as 20 mph on a long 6% grade and then gradually build up to your normal speed on the way down.

3. Maintain a steady speed on flat stretches. Varying your speed wastes fuel.

4. The slower you go at least down to the 40s, the better your fuel economy.

I drive in the low to mid 60s on Interstates and down in the 50s on windy, hilly roads.

David

[coachray]

Welcome to the forum. I drive 55-60

[The Gritz Carlton]

Whatever speed you run, you need to be in overdrive as much as possible with limited transmission downshifting. If you run too slow and transmission is continually downshifting, your RPM range goes up and you use more fuel per mile. Ideal speed will vary depending on terrain. You may have to run a bit faster in hilly terrain to keep the transmission in overdrive (or at least minimize downshifting). Just monitor your mileage as you go, listen to your engine and relative RPM and you'll find that perfect sweet spot. Generally 62-65 works best for me.

[Chance]

Originally Posted by 16ACE27

45 mph

I was going to say best economy is at 0 MPH, as when parked, but suppose he meant while driving.

I agree that 45 MPH may not be too far from best MPG in case of Compass because of small 3.5L V6 engine size. It is a given vehicles require less energy per mile the slower they cruise at steady speed on level road, so the main limiting variable that prevents best economy at even slower speeds is when engine becomes too inefficient due to insufficient load on it.

[16ACE27]

Yep 45 mph is fast enough to allow the engine to operate efficiently, but not so fast that wind resistance has an exponentially detrimental effect.