ScangaugeII - uphill xgauge to monitor for best ICE performance

Are you stating these slopes accurately, not interchanging degrees with slope-percents? 10 to 25 degrees means 18% to 47% grades, giving elevation changes of 180 to 490 feet in 0.2 mile. The higher slope is double the steepest paved segment I've heard about in this region, and is outright dangerous with any precipitation whatsoever.

With slopes this steep combined with photo speed cameras, I think hypermiling is out of the question. A lot of energy must be burned off by friction brakes on the downslopes.

 

OK, so sometimes we try to minimize engine-on time with a quick, efficient, pulse, then glide of some sort, whether regular or warp stealth.

In this case, however steep the hill is, it sounds there's no choice but to run the ICE for a given distance, instead of time. This means keeping instant mpgs high as possible during that time. There are basically two choices:

1. Keep speed up the slope but just maintain speed, don't speeding up. For this, just watch the instant mpgs on either Scangauge or the display. It really doesn't matter, the idea is just to see how little gas you can apply while keeping speed.

2. For no-traffic situations where the following downhill will give you momentum to speed back up some, drive with load, meaning, again, just use the minimum amount of gas, but this time to slowly bleed speed to a target speed at the crest of the hill.

Since you're already driving up a hill, it's going to be pretty efficient. Just focus on keeping the max mpg for either of those two options, you can't do much else.

If I misunderstood the situation let me know, but sometimes you just gotta get up that hill!

 

I didn't think you were complaining, just abnormally passionate about your mpgs, kinda like me

I looked at the street view of the road on Google maps - that road looks great for hypermiling. What I'm suggesting is different than a NICE-on, which is just neutral with the engine on. I'm saying that since you have to run the engine anyway, I would just barely keep speed up the hill. It's hard to tell on Google maps, but I have a feeling it's the sort of gradual grade where you can get around 40 mpg while going 20 mph-ish by keeping the foot verrry lightly on the pedal, or 50 mpg at 30 mph.

This is basically a low-speed super highway mode, since if you watch IGN and TPS when doing it, you'll find it around 14 and 18, respectively, or 13 and 19 - somewhere around there.

Another way to think of it is the bare minimum pedal needed to keep the engine on - if you let up the slightest bit it would slip into EV...that's the engine-on area I'm thinking of.

If the hill's a little steeper, just push a little more

Personally I don't find it too useful to watch Scangauge when I'm doing this sort of thing. It's more just maintaining speed with minimal energy, which is all by feel, and maybe a little speedometer watchin'.

 

I am a non-civil engineer.

Is this (from a Garmin topo) a reasonable representation of the section?


The steepest slopes here, at Annamarie CT and climbing out of Rock Creek, display as just under 4 degrees.

Toporoute.com shows a generally similar profile, but with more noise. It shows a steeper descent into Rock Creek (45 foot drop at 6 degrees), and a shallower climb out. It also varies between successive mapping attempts. But these computerized topos don't have real elevations for every point on the maps. Rather, they are just estimating elevations from some set of nearby datapoints, and I don't yet have a feel for how accurate they may or may not be along a requested track.

Personally, I vote with Mike -- ignore the ScanGauge on this kind of road, keep eyes on the road, and go by feel.

 

Maybe I need some re-educating. My understanding about maximizing MPG is that you want to use the engine at its peak efficiency when it's running. The method I read before is to aim for 1800RPM on the ICE. I had not heard of measuring GPH. Is that a better gauge of efficiency?

 

I grew up in Burtonsville. I know the roads your talking about. Your drive is so short your barely out of warmup, especially in winter. Since your ICE is running already your pulse and glides are already maxed also. I try to stay within 5 or 6 mph when P&Ging on little hills and valleys . Scanguage has a LOD display that can be useful on short uphills. By trial and error you pick a value that will get you up the hill at a suitable decreasing speed and try to keep it there. It will be different for each grade. Search here or at Cleanmpg for "Driving with load". For the distance your going you are doing quite well.

 

My personal feel, especially from the last few days of mixing different types of acceleration into my driving with way better results, is that that RPM area is good for initial acceleration, or anytime you need speed. If you don't, a light acceleration is nice for couple reasons:

1. It charges the battery more. If you only accelerate at 1800 RPM for pulse and glide, the battery will barely get charged since the engine's on for a short period of time, and more energy is going to the wheels. Each glide then progressively lowers your SOC. When you accelerate lightly the Prius is liable to throw a lot more amps into the battery.

2. Overall mileage is still about mileage over a distance (well, duh, I guess, let me explain better haha). If you pulse at 25 mpg up a hill because the engine is working efficiently, it sounds good, but in reality if no more speed is needed, and you're going to glide when you reach the top of the hill anyway, and you can get 40 mpg over the same distance, that's definitely preferable. Again, what I mentioned in number one above also happens during this time. Better mileage and better state of charge.

I've never really watched GPH either, can't comment on that.

 

I must disagree here. On slopes, instant MPG is meaningless without a proper accounting of changing gravitational energy. This is not included on any of the common display tools, and is well beyond the on-the-fly mental computation of most of us.

On rolling hills, MPG needs to optimized only over the complete up-and-down cycle, not over the ups and downs separately. My best hill results occur with burning fuel at an efficient ICE setting on the climb, then gliding down a shallow descent with no braking, ICE shut down, and no or very little electric propulsion. Not all hills are in the right range of slopes to pull this off well.

This sounds more like EV or Warp Stealth modes. A true glide puts no power into the electric motor. The reality is that we often add a little electric thrust to extend a glide, tuning it to better fit the situation. But do be aware that if the battery SOC drops sharply, then you aren't really gliding.

 

I've taken the liberty of making a paragraph up there haha...not sure why your formatting comes out so weird!

Back on topic, looks like Fuzzy and I will go back and forth agreeing with each other You're not gliding, you're using "stealth" mode, i.e. electric propulsion. This is actually something to be avoided for just the reason you say. 45% sounds "dangerously" low (I use the the word loosely, but basically I would never run the battery so far down...).

Judicious, sparing use of EV is great, but you're using it all the time without realizing. If you back off ever so slightly on the pedal for your glides, and have the HSI bar barely show at all, if it even does (not sure if it can be completely absent from view since I'm a Gen II driver, but if it can be, that would be ideal), that's what you're looking for - the glide. The more you bring up the HSI bar toward the center, the more in stealth mode you are. When you get the hang of keeping it far left for a good glide I think you'll be pleasantly surprised at the cool little bump up in mpgs you'll get.