EoC P&G'ers: Method for best MPG?

[i90east]

I drive on nearly empty US rural roads at night on a regular basis so I've been able to experiment with finding the optimal MPH range for getting the highest MPG numbers. What I've found is that the sweet spot seems to be 22-42 MPH, meaning coast down to 22, bump start and pulse up to 42, cut the engine, coast down to 22, repeat.

This spans the range of third gear from about 1,900-3,100 RPM and acceleration is pretty quick. When wind is negligible and the air temperature is at least somewhat warm this cycle nets an average of 80 MPG. Any speed higher than 42 MPH lowers the average due to the increased air resistance (no aero mods) and high engine revs. Any speed lower than 22 MPH bogs third gear and second gear is very inefficient.

I'm wondering if this method is similar to what other hypermilers are finding is best or if there's a better way. How do you go for the highest possible numbers in very ideal conditions (empty roads, no lights)?

[JRMichler]

Yup, you got it. Try different techniques, observe the MPG, repeat. If my travel routes allowed coasting down to 22 MPH, I would get much better mileage than currently. You lucky person, you.

[Fat Charlie]

Terrain dictates in my area.

Pulse up the hills, glide down- and it doesn't take much elevation change to have dramatic effects. My top speed is a combination of 45/psl/how much of a payoff my glide will see and my bottom speed depends on traffic, how long the glide is and how much of a hurry I'm in.

But near 45 is generally my most efficient steady speed on level ground- a 13 Fit MT with a grille block.

[PaleMelanesian]

Personally I'd try for 4th gear in those same speed ranges for a lower rpm, but I don't know your terrain. I almost never get up to 3000 rpm except maybe once every couple weeks. I like that speed range though, it's just about perfect.

[BenArcher006]

Haha I was just about to start the exact same thread!

Since I installed my kill switch, I did not see the improvement in my mpgs I thought I would have.

I cant figure out the sweet spot for optimal fuel economy. I can't really p&g in town because of traffic and stop lights. I dont know if its because of high winds but short highway trips seem to hurt my Mpgs and p&G does yield better results.

The sweet spot for my trucks for full economy is 52km/h in fifth gear with 20hg/in of Vacuum, gives me about 5.5l/100km depending on terrain.

I use my kill switch comming to a red light (in 5th gear) or coasting down a hill but other than that p&g eo does not improve my fuel economy and I cant figure why, heck I got better results EIC... Wtf?

I think I do not live in an area promoting Eoc or p&G due to terrain, somewhat dense traffic and to much stop lights.

[SDMCF]

Originally Posted by Fat Charlie

Terrain dictates in my area.

Pulse up the hills, glide down

Terrain is also important for me. Where I live it is undulating; not flat but few big hills.
I usually do the opposite to you. I try to pulse down the hills and glide up. My logic is that I use the engine where I get maximum acceleration for any given fuel usage, and I don't use the engine when it would have to battle against the terrain. Of course, many times I cannot glide all the way up a slope and I do have to use the engine going up hill, but my aim is to avoid that.

I don't have any data to show that my approach is better than yours, just my gut feeling. Can you convince me that I am wrong?

[Fat Charlie]

Potential energy and kinetic energy. I'd rather use potential as 100% of my power when possible instead of as a slight boost to the gas I'm burning on that same stretch.

Then there's load. Uphill is a greater load (gravity), as is higher speed (aero). You can minimize one of those loads but not the other.

If you have an SG or UG, it's very easy to check: On a consistent route, alternate methods and record your short trip results. Note variables and see which way works best for you.

[PaleMelanesian]

Power up and glide down gives you more consistent speed. Power down and you'll get going pretty fast, easily enough for a red & blue disco party. Then coasting up you'll slow to a crawl, also not good.

[SDMCF]

Consistent speed is not a target, or I would not P&G. My aim is to allow my speed to fluctuate between high and low speeds that I decide are acceptable. Whether I apply power uphill or downhill doesn't change that, so I am no more likely to over-speed or crawl than anyone else using P&G.

One thing that occurs to me is that if my average speed is the same as someone who pulses uphill, then typically my speed will be faster going downhill and slower going uphill. Surely reducing my speed when the terrain is working against me has to help my economy?

[Fat Charlie]

And letting the downhill carry you for free helps, too.

Burning gas to force the car downhill, which gravity is already doing for free, isn't very economical.