Consumption screen...

azzieo · Sep 1, 2006

I'd like to state from the beginning, that I don't mean to piss off the old(er) members of the board, but just wondering if other people find that odd:

I took a 10 mile trip this morning... first 5 miles took 5 mins to drive to the ramp, accelerate on the freeway, and then hit the traffic.... the next 5 miles - creeping away for 25 mins.. at the end - I look at my Consumption display and I see one bar at ~25mpg and 5 bars at ~75mpgs. Great!!!.. This visual with mostly high yellow bars looks like 66.67 avg mpg for these 30 mins!!!

Well - I'm no math god or anything but that's actually misleading visual presentation of the situation, which in fact is that I have driven 10 miles in 30 mins, with avg speed of 20mph and avg mpg of 37.5..... well - what seems like 66.67 is actually 37.5.

...and before someone jumps on me I'd like to state that I'm NOT complaining about 37.5, and that I DIDN'T enjoy my ride LESS, and I will still try to convince everyone I know that Prius is the greatest car on the market today....
BUT,.. the Prius has a computer that already has the really relevant data about my trip - the Avg.Speed., so it's mind boggling to me, why can't I see that information. The simplest thing to do is to at least put the miles traveled in those yellow bars, for every 5 min interval, which will give me some perspective of what I'm actually seeing.

Also - providing parallel data about AVG MPG and AVG SPD is the ONLY really relevant information, which would help me understand the optimal driving pattern for a given route... the 5 min chunks mean nothing unless I remember in my head what speed I was driving 5-10-15-20-25 mins ago, which is .... well... needless, if the computer already has that data, but just doesn't want to display it... bad computer bad bad bad..... or just another bad UI.

monkeypox · Sep 1, 2006

Hi
Well as for the comsumption screen, I have found it is not very accurate. When I fill up I check the screen and then break out the calc and do miles driven and amount of the good stuff I put in my tank and some times it is 10-15 MPG off. Now my calc is not wrong so what is the deal with the screen???? does it take in account what values u set up for the nav sys as in highway speed u set and city spd???? any way that is a monks 2 cents
Cheers
Monks

efusco · Sep 1, 2006

miles per gallon per 5 minutes....it is what it is. We've always said, all along, that the Consumption graph is only useful if you're traveling a steady speed. Any stopping, any significant speed changes and it's not an accurate representation of what you do.

Those of us who have CAN-View now have an MPG per mile readout and it is, I agree, much more useful.

curtissac · Sep 1, 2006

<div class='quotetop'>QUOTE(monkeypox @ Sep 1 2006, 04:58 AM) [snapback]312648[/snapback]</div>

Hi
Well as for the comsumption screen, I have found it is not very accurate. When I fill up I check the screen and then break out the calc and do miles driven and amount of the good stuff I put in my tank and some times it is 10-15 MPG off. Now my calc is not wrong so what is the deal with the screen???? does it take in account what values u set up for the nav sys as in highway speed u set and city spd???? any way that is a monks 2 cents
Cheers
Monks
[/b]
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The MFD consumption screen is probably correct. I would say that it is correct, but suppose there is always a small chance (really small chance) that something is wrong with yours.

I would bet that you calculator is also correct. But you are probably, unwittingly, giving the calculator bad numbers.

The problem with trying to calculate tank-by-tank gas mileage with your calculator is that you don't have a fixed capacity fuel tank. The Prius' fuel bladder capacity can vary by up to a gallon depending on temperature and other conditons. A variation of a quart or so happens all the time. When you drive a car with a small fuel capcity and 50 mpg efficiency, a one quart variation could show up as... 10 to 15 mpg when you try to calculate mileage at each fill up. Even with a conventional tank, when the pump shuts off can vary a little - but the bladder throws more of a curve ball at you.

I would suggest that you compare you calculator figures against the MFD over several tanks. When you average the two, you will probably see very close numbers.

Remember that the MFD is getting its data from the fuel delivery system. That system is very accurate - metering fuel to the injectors down microliters to keep the engine running right and emissions under control. I have no reason to think that the consumption numbers on my MDF are anything but dead-nuts accurate (or at least far more accurate than I could be at the gas pump).

kimgh · Sep 1, 2006

<div class='quotetop'>QUOTE(Curtis SAC @ Sep 1 2006, 08:53 AM) [snapback]312767[/snapback]</div>

The MFD consumption screen is probably correct. I would say that it is correct, but suppose there is always a small chance (really small chance) that something is wrong with yours.

I would bet that you calculator is also correct. But you are probably, unwittingly, giving the calculator bad numbers.

The problem with trying to calculate tank-by-tank gas mileage with your calculator is that you don't have a fixed capacity fuel tank. The Prius' fuel bladder capacity can vary by up to a gallon depending on temperature and other conditons. A variation of a quart or so happens all the time. When you drive a car with a small fuel capcity and 50 mpg efficiency, a one quart variation could show up as... 10 to 15 mpg when you try to calculate mileage at each fill up. Even with a conventional tank, when the pump shuts off can vary a little - but the bladder throws more of a curve ball at you.

I would suggest that you compare you calculator figures against the MFD over several tanks. When you average the two, you will probably see very close numbers.

Remember that the MFD is getting its data from the fuel delivery system. That system is very accurate - metering fuel to the injectors down microliters to keep the engine running right and emissions under control. I have no reason to think that the consumption numbers on my MDF are anything but dead-nuts accurate (or at least far more accurate than I could be at the gas pump).
[/b]
Click to expand...

I concur. On my recent 2000+ mile trip in the Prius, I kept the overall MPG for the whole trip. and achieved 49.8 MPG. I also kept all my gas receipts and, just after the last fillup, I divides the total miles traveled by the total # of gallons purchased for the trip. That came out at 49.96. So I totally believe in the accuracy of the display.

Beryl Octet · Sep 1, 2006

<div class='quotetop'>QUOTE(efusco @ Sep 1 2006, 08:09 AM) [snapback]312661[/snapback]</div>

miles per gallon per 5 minutes....it is what it is. We've always said, all along, that the Consumption graph is only useful if you're traveling a steady speed. Any stopping, any significant speed changes and it's not an accurate representation of what you do.

Those of us who have CAN-View now have an MPG per mile readout and it is, I agree, much more useful.
[/b]
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I think a view that showed miles per gallon per 5 miles, or MPG / miles would be useful. I like the bar showing instaneous mileage while I drive, but with stop and go etc., I don't find the graph that useful. I really wish the energy display had a bar on the side, then I'd probably stay on that screen most of the time.

Sho-Bud · Sep 1, 2006

The consumption screen is correct, but you can't use it to calculate the average consumtion of your trip.
Because you don't know how many miles you drove during that 5 minute period.

Ichabod · Sep 1, 2006

Stopping looking for things to find fault with in your fabulous new car, azzieo If you didn't have MPG/5min display then you wouldn't be able to fake some awesome-looking screens of full bars!

azzieo · Sep 1, 2006

<div class='quotetop'>QUOTE(Ichabod @ Sep 1 2006, 01:04 PM) [snapback]312858[/snapback]</div>

Stopping looking for things to find fault with in your fabulous new car, azzieo If you didn't have MPG/5min display then you wouldn't be able to fake some awesome-looking screens of full bars!
[/b]
Click to expand...

Thanks for the advice...

qbee42 · Sep 1, 2006

How about a 3D chart showing mileage and distance in five minute increments.

Tom

lskarha · Sep 1, 2006

I always thought the screen should show mpg over distance not time.
It always looks odd after going thru a long drive thru line.
-Lee

Ichabod · Sep 1, 2006

Well, from what I know, the MacPrius project is heading into a direction where all kinds of cool apps could be made to read and display data in various ways using CAN-view. Customizable to your heart's delight (within your programming abilities).

Of course, that's only useful for people with CAN-view and a computer in their car (i.e. not me )

Charles Suitt · Sep 1, 2006

<_< In detailed records, over two years driving my 2004, I find the Consumption Display to be over 97% accurate compared to pumped gallons vs. miles traveled. I'd call that "Close Enough for Government Work!"

As an aside: Having the Consumption Display on, I have learned to drive more economically - coasting to an upcoming traffic stop (traffic permitting) - setting Cruise Control (usually -40 MPH intown) - in general, being more conscious of my driving habits.

JohnTortorici · Sep 1, 2006

azzieo @ Sep 1 2006 said: ↑

312642[/snapback]</div>

I'd like to state from the beginning, that I don't mean to piss off the old(er) members of the board, but just wondering if other people find that odd:

I took a 10 mile trip this morning... first 5 miles took 5 mins to drive to the ramp, accelerate on the freeway, and then hit the traffic.... the next 5 miles - creeping away for 25 mins.. at the end - I look at my Consumption display and I see one bar at ~25mpg and 5 bars at ~75mpgs. Great!!!.. This visual with mostly high yellow bars looks like 66.67 avg mpg for these 30 mins!!!

Well - I'm no math god or anything but that's actually misleading visual presentation of the situation, which in fact is that I have driven 10 miles in 30 mins, with avg speed of 20mph and avg mpg of 37.5..... well - what seems like 66.67 is actually 37.5.

...and before someone jumps on me I'd like to state that I'm NOT complaining about 37.5, and that I DIDN'T enjoy my ride LESS, and I will still try to convince everyone I know that Prius is the greatest car on the market today....
BUT,.. the Prius has a computer that already has the really relevant data about my trip - the Avg.Speed., so it's mind boggling to me, why can't I see that information. The simplest thing to do is to at least put the miles traveled in those yellow bars, for every 5 min interval, which will give me some perspective of what I'm actually seeing.

Also - providing parallel data about AVG MPG and AVG SPD is the ONLY really relevant information, which would help me understand the optimal driving pattern for a given route... the 5 min chunks mean nothing unless I remember in my head what speed I was driving 5-10-15-20-25 mins ago, which is .... well... needless, if the computer already has that data, but just doesn't want to display it... bad computer bad bad bad..... or just another bad UI.
[/b]
Click to expand...

Hey Folks. Ok, I am new to this Forum, and just recently purchased a 2006 Prius. This graph for the consumption has been driving me NUTS, so I finally just sat down and did the math. Some of the things that you have to take into consideration when trying to figure out what the bar really means, is how far you traveled in that 5 minutes, how much of that was stop and go, and how often you are at the 100mpg (which really is misleading, because when the engine is shut off, it's getting Infinite MPG). So, here we go.....

Imagine this trip in 5 minute increments:

0-5: Start car, pull out of drive way, make it to first major rd (2.5 miles, 25mpg avg, 30mph avg)
6-10: On major rd normal driving (3.75 miles, 75 mpg avg, 45mph avg)
11-15: On highway normal driving (5 miles, 52mpg avg, 60mph avg)

The easy thing here is to look at this and say (25 + 75 + 52)/3 = 50.66 mpg avg in that 15minutes. But that's not the reality, because the distances in each 5 min segment (hence the amount of actual fuel burned in that 5 minutes) is completely different.

In the first 5 minutes, even though the mpg is 25, the relative distance is very short. In the second 10 minutes, the mpg is very high, but likely stop and go traffic, with lots of time of the engine shut off, so the amount of fuel burned again will be minimal. In the last 5 minutes, the car will probably keep the engine going, with the elec motor assisting now and then. So to figure out what the realy mpg for this 15 minute trip really is, you have to know the amount of fuel burned in each 5 minute span.

2.5 miles] 25mpg = .10 gallons of gas
3.75 miles @ 75mpg = .05 gallons of gas
5 miles @ 52mpg = .096 gallons of gas

Total gas used (TGU): .246 gallons
Total distance (TD): 11.25 miles
Actual mileage (AM) = 45.7mpg

Formula:
(1/TGU) * TD = AM

Use this formula, and I think you will find the cars computer to be DEAD accurate. I just thought I would make my first post amazing difficult to understand.
Click to expand...

Ichabod · Sep 1, 2006

Welcome JJT2006. You've proven yourself to be in the right spot for people over-thinking their relationship with their car!

It's now well established that the consumption display is in MPG/5min, not MPG/mile. Hopefully some day they'll build in an option to switch between the two, but meanwhile, eyes back on the road, not the calculator!

azzieo · Sep 1, 2006

JJT2006Prius @ Sep 1 2006 said: ↑

312888[/snapback]</div>

Hey Folks. Ok, I am new to this Forum, and just recently purchased a 2006 Prius. This graph for the consumption has been driving me NUTS, so I finally just sat down and did the math. Some of the things that you have to take into consideration when trying to figure out what the bar really means, is how far you traveled in that 5 minutes, how much of that was stop and go, and how often you are at the 100mpg (which really is misleading, because when the engine is shut off, it's getting Infinite MPG). So, here we go.....

Imagine this trip in 5 minute increments:

0-5: Start car, pull out of drive way, make it to first major rd (2.5 miles, 25mpg avg, 30mph avg)
6-10: On major rd normal driving (3.75 miles, 75 mpg avg, 45mph avg)
11-15: On highway normal driving (5 miles, 52mpg avg, 60mph avg)

The easy thing here is to look at this and say (25 + 75 + 52)/3 = 50.66 mpg avg in that 15minutes. But that's not the reality, because the distances in each 5 min segment (hence the amount of actual fuel burned in that 5 minutes) is completely different.

In the first 5 minutes, even though the mpg is 25, the relative distance is very short. In the second 10 minutes, the mpg is very high, but likely stop and go traffic, with lots of time of the engine shut off, so the amount of fuel burned again will be minimal. In the last 5 minutes, the car will probably keep the engine going, with the elec motor assisting now and then. So to figure out what the realy mpg for this 15 minute trip really is, you have to know the amount of fuel burned in each 5 minute span.

2.5 miles] 25mpg = .10 gallons of gas
3.75 miles @ 75mpg = .05 gallons of gas
5 miles @ 52mpg = .096 gallons of gas

Total gas used (TGU): .246 gallons
Total distance (TD): 11.25 miles
Actual mileage (AM) = 45.7mpg

Formula:
(1/TGU) * TD = AM

Use this formula, and I think you will find the cars computer to be DEAD accurate. I just thought I would make my first post amazing difficult to understand.
[/b]
Click to expand...

Great.... now read back your post and mine, and you'll see that they're excatly the same, except for the fact that I was commenting on the UI, and not on the accuracy of the computer.
Click to expand...

Ichabod · Sep 1, 2006

Don't be mean, azzieo, he's just agreeing with you... in his own special way

ken1784 · Sep 2, 2006

<div class='quotetop'>QUOTE(azzieo @ Sep 1 2006, 06:31 PM) [snapback]312642[/snapback]</div>

I took a 10 mile trip this morning... first 5 miles took 5 mins to drive to the ramp, accelerate on the freeway, and then hit the traffic.... the next 5 miles - creeping away for 25 mins.. at the end - I look at my Consumption display and I see one bar at ~25mpg and 5 bars at ~75mpgs. Great!!!.. This visual with mostly high yellow bars looks like 66.67 avg mpg for these 30 mins!!!

Well - I'm no math god or anything but that's actually misleading visual presentation of the situation, which in fact is that I have driven 10 miles in 30 mins, with avg speed of 20mph and avg mpg of 37.5..... well - what seems like 66.67 is actually 37.5.[/b]
Click to expand...

I assume you did the math...
(25 + 75 * 5 ) / 6 = 66.67 mpg
That's wrong math.

The correct one is...
The first 5 min ... 5 miles at 25 mpg ... 0.2 gallons consumed
The next 25 min ... 5 miles at 75 mpg ... 0.0667 gallons consumed
The total 10 miles consumed 0.2667 gallons, which means 37.5 mpg avg.
What an accurate display!

Ken@Japan

Frank Hudon · Sep 2, 2006

holiday trip CAN-view results. only difference between what is shown in this picture and that actual mileage is about 34 miles that I missed saving. For those challanged by converting Liter per hundred Kilometers check out this site.
http://www.packexpo.com/education/ref/fuel_conv_cal.shtml
this is in mileage not time as the MFD shows

jburns · Sep 2, 2006

<div class='quotetop'>QUOTE(ken1784 @ Sep 2 2006, 01:24 AM) [snapback]312945[/snapback]</div>

I assume you did the math...
(25 + 75 * 5 ) / 6 = 66.67 mpg
That's wrong math.

The correct one is...
The first 5 min ... 5 miles at 25 mpg ... 0.2 gallons consumed
The next 25 min ... 5 miles at 75 mpg ... 0.0667 gallons consumed
The total 10 miles consumed 0.2667 gallons, which means 37.5 mpg avg.
What an accurate display!

Ken@Japan
[/b]
Click to expand...

Wellllllll. Lets see here what you used here. The display doesen't show gas used per five minutes. The display doesn't directly show miles driven each five minutes. Do you juggle a pad and pencil on the steering wheel each five minutes to write down the milage driven and do the division?

Actually it's your calculation that's accurate.

Consumption screen...

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