economy better in the hills?
 

New here....been trying to post a question without success, so this is another test

Not sure if you're actually asking, but here's my take...Theoretically, yes, driving in the hills should be more economical. Your engine will be(can be) running in its more efficient zone going up hill...and you can coast down. Its basically pulse and glide, only rather than picking up speed, you're picking up potential(gravitational) energy.

On the other hand, if your vehicle is particularly heavy, you'd be using a lot more power to climb the hill, and might pick up too much speed and have to brake(a pure waste of energy) on the downhill side. You might even push your engine past it's efficient zone getting up the hill in the first place.

I drove my first car in the rolling hills around Willamina, OR. It had marginal cooling so it would overheat going uphill and cool down going downhill.

Best fuel economy I've had has been in the hills. There's about 30 miles on highway 26 you can mostly engine off coast coming down from Mt. Hood. From Government Camp to Sandy.

Yes.

Half of my drive from rural east Texas to Dallas is rolling hills (up and down 100 ft or so) and half is very flat. I get better mileage in the hilly section.

This is true even in the family van with its automatic transmission. It's harder work on that, because you have to minimize downshifting on the climbs, but even with some of that, it's more efficient than the flat land with steady speed.

Just getting up there, where the air is thinner, means less air resistance and less pumping loss in the engine on partial load, meaning you get more power from the same amount of fuel.

My personal best was top of the Siskyou Pass to the first exit to Ashland.

I'm sure this is a bot, but let's keep feeding the thread anyhow.

My best coast was coming down from Yosemite. Started with an empty traction battery, and with regen got 100% full, which is approximately 3 kWh; good for 14 miles of EV range. After the battery filled, I had to put the Prius into B mode which uses engine compression to slow the vehicle. Don't know how many miles it was, but it had to be a lot.

If I can maintain 70-75 MPG going up a hill without losing too much speed, the coast or 125+ MPG going down the hill returns the same or slightly better fuel economy than a steady 85 MPG - 100 MPG cruise. If the car kicks out of lean burn or I have to downshift on a hill, my MPG seems to be worse, but not by much.

Now those West Virginian hills will be a challenge this Friday...

Agreed. I would think it depends on the steepness of the hill and the excess power of the vehicle. The closer a car is to running at high load / peak BSFC RPM, the shallower the hill needed, with fuel economy maximum approaching 100% on flat terrain the lower the power of the vehicle.