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Discussion Starter · #1 ·
It would interesting to show elevation graphs--that you see sometimes for bicyclists--for us Prius drivers who have a regular commute to work or whatever (I'd say at least 3 days a week, like mine). You'd indicate what your average mileage is along with the number of days a week you commute. It would be a good comparison of how the terrain we travel shows one of the factors that determines our mileage.

Ideally, it would simply work like imputing driving directions at Mapquest, with the result showing the elevation graph. It would be great if this were readily available.
 

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Or a short summary...

Two cups of coffee before work. I'm up. It's all down hill from there. :wink:
 

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wayneswhirld said:
It would interesting to show elevation graphs--that you see sometimes for bicyclists--for us Prius drivers who have a regular commute to work or whatever (I'd say at least 3 days a week, like mine). You'd indicate what your average mileage is along with the number of days a week you commute. It would be a good comparison of how the terrain we travel shows one of the factors that determines our mileage.

Ideally, it would simply work like imputing driving directions at Mapquest, with the result showing the elevation graph. It would be great if this were readily available.
It would be a neat thing, however I commute 5 days a week and take exactly the same route to and from. Since every hill I coast down on the way in has to be climbed on the way out the average is flat. Mileage variations for me seem more likely to be due to traffic conditions. (It's a two lane road and if the Hummer in my rearview wants to do 80, I'm gonna put the pedal down.)
 

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Discussion Starter · #4 ·
pogo said:
...I commute 5 days a week and take exactly the same route to and from. Since every hill I coast down on the way in has to be climbed on the way out the average is flat.
Actually, I have found that the for hill I traverse in my commute, I consistantly use twice, or close to twice the fuel going up as I save coming down. Try it and see what your current MPG readout is before/at peak/after.
 

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wayneswhirld said:
Actually, I have found that the for hill I traverse in my commute, I consistantly use twice, or close to twice the fuel going up as I save coming down. Try it and see what your current MPG readout is before/at peak/after.
Hmmm. Good point. Although the average of the topography may look flat, it may not produce the same result as flat. I'm not sure I know how to do the experiment you suggest?
 

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Discussion Starter · #6 ·
pogo,
It works ideally in my situation since I go both up and down a hill in one direction. It's even in elevation both sides (about 2,450 at peak). So if at the start of ascent for example, my MPG readout is 49.4 and at the top it reads 48.2, at the end of descent it would typically read 48.8.

In your case, you could get the start and peak MPGs like I do, and then on your return commute, you could mark your MPG at the peak again and see what it is at the bottom. But as you'd figure, it's not as exacting since the wind conditions could be different in each direction and if the evenness of topography on each side is not close, this won't work.
 

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Also what could affect it is the use of regen. If in going down you have to press on your brakes or even if you just let go of the gas, you are using regen to simulate drag, which though better than a conventional car, is still not 100% efficient.

But if you glide down the hill, speed limits and safety permitting, or the hill is shallow enough where you still have to apply power (just not as much) you should be close.
 

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Discussion Starter · #8 ·
DanMan32 said:
Also what could affect it is the use of regen. If in going down you have to press on your brakes or even if you just let go of the gas, you are using regen to simulate drag, which though better than a conventional car, is still not 100% efficient.

But if you glide down the hill, speed limits and safety permitting, or the hill is shallow enough where you still have to apply power (just not as much) you should be close.
That would pretty much answer why it doesn't come out even. If I just glided down, I'd probably fly over the guard rail at the 1st hairpin turn doing about 70 :lol:
 

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As a geek experiment I used google earth to map my path to work and discovered that the path I take to work has a net loss of about 700 feet (on a 10 mile trip so I get 3 or 4 full bars on the trip to work. I had to find a different route home that was more flat and shorter up hill. But the DEM info on Google earth was really helpful.
 

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wayneswhirld said:
pogo,
It works ideally in my situation since I go both up and down a hill in one direction. It's even in elevation both sides (about 2,450 at peak). So if at the start of ascent for example, my MPG readout is 49.4 and at the top it reads 48.2, at the end of descent it would typically read 48.8.
I'd say it works sort of in your case. Well enough for you to conclude (which you did) that you don't regain everything lost on the downhill side of the trip, but you've got a hill and I've got a series of hills. Based on the resolution of the display, and not knowing what rounding algorithm they're using, the uncertainty of your differential measurement is at best .1 and at worst .2. In order for the experiment to produce useable information the actual differential you're trying to measure has to be significantly greater than the measurement uncertainty. In your case the displayed differential of .6 could be as little as .4 or as great as .8, but it unquestionably exists. For my case nothing I encounter (in the way of hills) produces a change greater than .1 which is within the best case measurement uncertainty -- so I can't really get any useful info.
 

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wayneswhirld said:
pogo said:
...I commute 5 days a week and take exactly the same route to and from. Since every hill I coast down on the way in has to be climbed on the way out the average is flat.
Actually, I have found that the for hill I traverse in my commute, I consistantly use twice, or close to twice the fuel going up as I save coming down. Try it and see what your current MPG readout is before/at peak/after.
That's odd. Going up Mt. St. Helens a year and a half ago, I found that at the 'bottom' (freeway exit/entrance,) I actually ended up HIGHER on the MFD when I ended than when I started. At the time, I noted my miles/mileage when exiting the freeway, which I remember was under 50.0, when I reached the top (parked at the observatory, obviously WELL under 50.0,) and again when I hit the freeway entrance again (which I remember had just hit exactly 50.0, marking an IMPROVEMENT by going up the hill then coming back down, I've got a wonderful photo of the MFD showing all 100+MPG for the whole half hour.) Taking the freeway home, I struggled, and kept it within 0.1 of 50.0 until I hit the hill right before my freeway exit, which always seems to drop it 0.2 or 0.3. When I finally got home, I was at 49.9 (I can recover SOME of the freeway hill loss, but never all of it, but I generally do gain it back if I head back down that freeway hill.) :-(
 

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wayneswhirld said:
DanMan32 said:
Also what could affect it is the use of regen. If in going down you have to press on your brakes or even if you just let go of the gas, you are using regen to simulate drag, which though better than a conventional car, is still not 100% efficient.

But if you glide down the hill, speed limits and safety permitting, or the hill is shallow enough where you still have to apply power (just not as much) you should be close.
That would pretty much answer why it doesn't come out even. If I just glided down, I'd probably fly over the guard rail at the 1st hairpin turn doing about 70 :lol:
When I did this in my 2004 HCH with the clutch in, I scored 3MPG better, 88MPh, and a :cry: $186 ticket :cry:
 

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Well I like the idea! My impression from reading various people's claims of mileage achieved is that terrain (and sociology) dominate over technique. People from flat states and relatively mellow states do better than people from hilly, intense states. I rarely break 46, and often get only 43 mpg on a tank, but I have a commute that is dominantly uphill one way and dominantly downhill the other, and if I commute during normal hours, the traffic doesn't permit driving as slowly as 65, let alone 55. And of course, variations in speed are entirely driven by the traffic speed -- no gaining on the downs and slowing on the ups. I can get some awesome mileage for the net-downhill leg, but the uphill eats it. Regen is good, but not 100% efficient, and I suspect you never gain back on the downhill what you spent on the uphill. So I'd love to see the terrain-correlated averages. Then the only remaining variable we need is the traffic-density/speed-limit factor.

I have discovered that moving house is a real mileage killer. We moved about 2 miles and on the tank where I was going back and forth with a loaded car I got a mere 37 mpg.
 

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Discussion Starter · #14 ·
ehurtley said:
wayneswhirld said:
pogo said:
...I commute 5 days a week and take exactly the same route to and from. Since every hill I coast down on the way in has to be climbed on the way out the average is flat.
Actually, I have found that the for hill I traverse in my commute, I consistantly use twice, or close to twice the fuel going up as I save coming down. Try it and see what your current MPG readout is before/at peak/after.
That's odd. Going up Mt. St. Helens a year and a half ago, I found that at the 'bottom' (freeway exit/entrance,) I actually ended up HIGHER on the MFD when I ended than when I started.
ehurtley, I'd think that the typography of that hill was much briefer on the upside and much longer and gradual on the downside. If not, than I don't know what to think. The hill I go on is 3 miles long each side.
 

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wayneswhirld said:
ehurtley said:
That's odd. Going up Mt. St. Helens a year and a half ago, I found that at the 'bottom' (freeway exit/entrance,) I actually ended up HIGHER on the MFD when I ended than when I started.
ehurtley, I'd think that the typography of that hill was much briefer on the upside and much longer and gradual on the downside. If not, than I don't know what to think. The hill I go on is 3 miles long each side.
I think it depends on what the SOC was and other factors too. You'd have to look at just the climb and descent as separate entities to start with! THen you'd need to factor in the SOC at the beginning of the ascent and the beginning of the descent. There's more here than gravity!

BTW, if you do much hiking, going up and down doesn't average out to flat! It's much more taxing as even downhill is taxing in a different way. Not 100% applicable to the car, but...
 

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wayneswhirld said:
ehurtley said:
wayneswhirld said:
pogo said:
...I commute 5 days a week and take exactly the same route to and from. Since every hill I coast down on the way in has to be climbed on the way out the average is flat.
Actually, I have found that the for hill I traverse in my commute, I consistantly use twice, or close to twice the fuel going up as I save coming down. Try it and see what your current MPG readout is before/at peak/after.
That's odd. Going up Mt. St. Helens a year and a half ago, I found that at the 'bottom' (freeway exit/entrance,) I actually ended up HIGHER on the MFD when I ended than when I started.
ehurtley, I'd think that the typography of that hill was much briefer on the upside and much longer and gradual on the downside. If not, than I don't know what to think. The hill I go on is 3 miles long each side.
I think it depends on hill grade. It'll be average out if the hills are gradual enough.

FYI...
Following is my collected data of NHW-20 Prius driving highway with CC set at 91km/h(actual was 85 km/h).
Code:
section km  mileage   alt change
    28km    24.5km/L      127m
    15km    18.7km/L      248m
    62km    40.8km/L     -663m
Saw such various mileage results even on constant speed.
The reason was the altitude change on each sections.
If we use 0.106L/100m fuel to cover the potential energy, the table becomes as follows;
Code:
section km  fuel used  fuel pot  fuel adj  mileage
    28km      1.14L     -0.13L    1.01L    27.8km/L
    15km      0.80L     -0.26L    0.54L    27.8km/L
    62km      1.52L      0.70L    2.22L    27.9km/L
Now, we can see constant about 27.8km/L mileage number for a virtual flat road.

The 0.106L/100m equals to 0.00854USgallons/100ft.

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wayneswhirld said:
ehurtley said:
That's odd. Going up Mt. St. Helens a year and a half ago, I found that at the 'bottom' (freeway exit/entrance,) I actually ended up HIGHER on the MFD when I ended than when I started.
ehurtley, I'd think that the typography of that hill was much briefer on the upside and much longer and gradual on the downside. If not, than I don't know what to think. The hill I go on is 3 miles long each side.
Well, the drive to Johnston Observatory from the freeway is about 51 miles from the main freeway entrance I was mentioning above, and is about a 4000 foot elevation gain over that distance (according to Google Earth, the freeway entrance is at 83 feet MSL, and according to the Johnston Ridge Observatory website, the observatory is at 4314 feet MSL.) The drive back I'm referring to is the exact reverse drive. The battery was at 6 bars when I started, and 8 when I finished (going down 4000 feet, I had a display of all 100+MPG bars.)

Here's a Google Maps link to the route. (The forum software doesn't want to make it a proper link, so I've TinyURLed it.)
 
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