Should I take the shorter but steeper route, or longer but all-flat route?

[more4less]

Hello,
I'm not sure which is more fuel efficient:

A) The route that is 14.5 kilometres (9 miles) shorter but has more ups and downs
OR
B) The route that is 14.5 km (9 mi) longer but is more highway driving and is almost all on level ground.

Pls help.

We have a 1995 4-door Civic Lx, automatic.

[ksstathead]

What is the trip distance? How steep?

9 miles on a 500 mile trip is a different answer than 9 miles on a 5 mile trip.

[RedylC94]

Hills don't necessarily hurt your fuel consumption per mile, depending on the details. They do if you have to brake on the way down because of excessive speed, curves, stop signs, or whatever.

[alvaro84]

Originally Posted by RedylC94

Hills don't necessarily hurt your fuel consumption per mile, depending on the details. They do if you have to brake on the way down because of excessive speed, curves, stop signs, or whatever.

If you don't have to brake for such reasons, a hilly route can even be better. At least it works for me quite well.
Hills can make the route a natural pulse&glide. Others DWL and it works for them too.

[PaleMelanesian]

It also depends on the vehicle. A manual transmission can do well in the hills but an automatic will struggle to get good mpg.

[basjoos]

Hills are a natural form of pulse and glide, and will give you better mileage so long as the downhills aren't steep enough to produce excessive speed or steep and curvy enough to force you to have to brake (engine, friction, or regenerative) on the downhill portions of the route. Sharp curves also increase your tire's rollling resistance while negotiating the curve. Conversely, if the elevation increase is significant enough, the thinner air at higher elevations will give you better mileage on the higher altitude portions of your route.

[shiNIN]

I only have a bike so I can talk only about that.
My best tanks always involve (not too steep) hills. Those gives the best FE results in my case, my speed is obviously low in sharp turns, I glide a lot - steep ones aren't as good, because I need to brake instead of gliding, vehicle and skill matters a lot too.
Flat highways are the worst for my FE, I barely can use any hypermiling techniques, a bike isn't as streamlined as a car so my glides are cut short. (Besides, a highway is boring enough at higher speed, I can't ride as slow as in a curvy hilly landscape.)

[some_other_dave]

It depends.

There are a lot of variables, ranging from how long the original trip is to what kind of vehicle you have. To definitively answer that question, you have to find out how much fuel you are using on each route. You can use a trip MPG readout if your vehicle has one, or an aftermarket gauge (SG II, Ultra Gauge, etc.) if you have a car that is 1996 or later.

Other options may be possible in some other cases (e.g., MPGuino for older cars with electronic fuel injection and an electronic speed sensor of some kind). In other cases, you may just have to drive only the one route for a tank worth of gas, then compare that to driving only the other route for a tank of gas.

-soD

[Mendel Leisk]

There are so many variables. If you can measure your fuel consumed on both routes that should help you make a decision. Personally I'd go for the route without hills, even if there's a slight fuel disadvantage, just because it tends to be less wear-and-tear, on the engine and brakes.

Hmm, guess I'm saying more-or-less the same as the post above.

[herm]

I wish we had some hills in South Florida..