How accurate/inaccurate is your mpg display??

Ok, I know this is a bit premature, because today was the first fill up and the tank wasnt full when I bought it. But the display showed 36 mpg tank average and either it's very pessimistic or that seems pretty low for conservative (up to this point) riding. I know that until I run a few tanks and do actual miles/gallons to get a baseline it's all just speculation. The coolant temp gauge reads a steady three bars after it gets warmed up (I read the threads on the failed stat causing poor mileage) and the brake rotors aren't hot.
What sort of mileage do most really get in comparison to the display? Most vehicles I've owned get worse than the computed display. OCD is sort of kicking in and yes I have tracked the mileage on all the other bikes/vehicles I've owned other than the off road stuff. The Kawasaki Concours 1000s typically got 45-50 in similar duty and figured the higher geared fuel injected ST might do as well.
Any other such deranged owners feel free to chime in with their observations.

Doing interstate speeds 70 to 80 mph I get 260 to 270 miles out of a tank. When I fill up the most I have ever put in the tank is a little over 6 gallons. About 45 miles per gallon. Try to never run below 1/4 of a tank. It is hard not to run the ST but if you drive on the conservative side you can get better. The ST likes fresh fuel. If the tank of fuel is a month or so old I have notices less fuel mileage but goes back to the regular mileage after fresh fuel. I rode the Natchez Trace Parkway for a few hundred miles where the max speed is 50 mph and got 50 mpg. Around town in stop and go traffic I get around 270 out of a tank of fuel. 2012 ST1300. Paul.

This a bit off-topic, but, my '05 ST1300A speedometer inaccuracy can vary from 4mph - 11mph depending upon road speed. FaSTer generates higher inaccuracy. Hope this helps??

Bought mine new from local dealer, and depending upon altitude, humidity, ambient temperature, wind direction and speed has consistently been averaging 32mpg-41mpg.


thank you,
-Elliot

More off topic:

My bike ran out of gas when the display was flashing 23 miles remaining.

If I fill the tank full while on the sidestand the display shows only 7/8 tank.

The display only ever shows 8 bars full if I fill the tank to the brim while on the centerstand, and even then within 10 miles the display reads 7/8 tank.

I don't trust the gas guage at all.

jettawreck said:

Any other such deranged owners feel free to chime in with their observations.

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With a little over 500 data points I can tell you that I typically average 1.99 MPG lower on the indicated average verses what I calculate per tank full.

FYI, I always perform the same ritual when filling my tank: Place bike on centerstand and fill the tank to the same spot at the top of the tank and make sure I reset the average MPG indicator. I then almost always run the tank down till the last segment appears on the fuel gauge.

You probably won't get a real feel for your mileage until you run several tanks with the bike.

As you can see by this graph, MPG per tank can vary substantially and yet the indicated MPG value calculated by the bike does tend to follow these differences quite closely.

As always YMMV...

STill STylin said:

This a bit off-topic, but, my '05 ST1300A speedometer inaccuracy can vary from 4mph - 11mph depending upon road speed. FaSTer generates higher inaccuracy. Hope this helps??

Bought mine new from local dealer, and depending upon altitude, humidity, ambient temperature, wind direction and speed has consistently been averaging 32mpg-41mpg.


thank you,
-Elliot

Click to expand...

sort of typical with most, at least the prior bikes I've had, and it can vary a fair bit depending on tire choice.
I haven't put the GPS to this one yet to see how much (not "if") it's off. Garmin will go for a ride with tomorrow and figure that out. Good reminder to know what your true speed is.
Oddly, my VWs speedo are off about 3 mph @ 60 but the odometer is very close to correct per the Garmin.

SanDiegoDan said:

More off topic:

My bike ran out of gas when the display was flashing 23 miles remaining.

If I fill the tank full while on the sidestand the display shows only 7/8 tank.

The display only ever shows 8 bars full if I fill the tank to the brim while on the centerstand, and even then within 10 miles the display reads 7/8 tank.

I don't trust the gas guage at all.

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yep, I always fill on the centerstand to the same level as closely as possible to try to reduce filling errors entering into the variable(s).
Have not got to the point of testing the range or accuracy of the gauge yet, although it showed three bars remaining and filled 4.5 gallons and after filling showed "full", even after 25 miles home.
Sounds like you may need to "adjust" the float arm in the tank? That was common on the older Concours. I added a resister to the sender unit and after that the gauge (not digital) read quite accurate. It was a common mod from the Concours owners forum. Much easier than getting into adjusting the float arm.

Scooter said:

With a little over 500 data points I can tell you that I typically average 1.99 MPG lower on the indicated average verses what I calculate per tank full.

FYI, I always perform the same ritual when filling my tank: Place bike on centerstand and fill the tank to the same spot at the top of the tank and make sure I reset the average MPG indicator. I then almost always run the tank down till the last segment appears on the fuel gauge.

You probably won't get a real feel for your mileage until you run several tanks with the bike.

As you can see by this graph, MPG per tank can vary substantially and yet the indicated MPG value calculated by the bike does tend to follow these differences quite closely.

As always YMMV...

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Excellant info and well done. Never got around to charting it like that (just kept a journal type log) but with the VW TDI used to enter all the fills with the "Fuely" site. Haven't updated in a long time, but here.....http://www.fuelly.com/car/volkswagen/jetta/2001/jettawreck/22381
Sort of sad that I get better mpg with the car than the bikes, but that's the way it is, but the bike is mostly for fun. Although, mileage games are sort of fun too.
Yep, always filled on centerstand to same level to minimize fill variables. I tend to run most things as close to empty as I can to learn the real range it has and also larger fill amounts reduce the amount of fill variance.
It usually does take several fills to get a decent handle on what to expect, and differences in routine can throw the average a curve.
So, aprox a steady 2 mpg has been your variance from the display indicated to actual? That's what the main question was and that seems typical of most on board systems. Optimistic a bit. Too bad there isn't a way to calibrate the display like there is with the ScanGauge trip computers I use in the TDIs. They are great and simply plug into the OBDII port.
Thanks a bunch for the feedback!

jettawreck said:

But the display showed 36 mpg tank average and either it's very pessimistic or that seems pretty low for conservative (up to this point) riding. I know that until I run a few tanks and do actual miles/gallons to get a baseline it's all just speculation.

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The fuel consumption display tends to read about 3 MPG less than what I calculate based on what's on the trip odometer and the gas pump. Leave your OCD at home; that's just how it is.

The Kawasaki Concours 1000s typically got 45-50 in similar duty and figured the higher geared fuel injected ST might do as well.

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The Conk is a different bike from a different era. The ST is designed and built for eating highway miles at 60-65 MPH, and that's where it drinks the least gas. Prior to 2006, when they started putting [-]saltpeter[/-] ethanol in the fuel, 50 MPG under those conditions was attainable; these days that figure is a few MPG less. The further you get from that ideal, the worse it gets, and high 30s in around-town and back-roads riding isn't unusual.

If you're still on your first or second full tank, you and the bike have probably not become fully acquainted yet, and that will factor into it as well. My advice would be to spend some time with it, get to know where the engine does its best work, spend less time worrying about the absolute number and spend more time on maintaining a grin.

--Mark

The first two cars I owned did not have working fuel gauges so I kept track with a mileage log in a pocket sized spiral notebook. This started a long interest in tracking mpg. Fuelly is my 21st century spiral notebook.

My ST gets about 2 mpg better than the dash indicator for avg mpg or instant mpg shows tracked over 10,000+ miles. My odometer, depending on the tire in use and its wear, is 1.5 to 1.8% optimistic. As the tire wears the correction factor rises. I correct the trip odometer reading to close-to-actual miles traveled and divide by gas pump gallons purchased to get as accurate info as I can. Or I use GPS mileage if the GPS is on the bike for that tank. I regularly checked the odometer against known distances until I was very certain of accuracy. OCD. If I'm not out of town I buy gas almost always at the same station and the same gas pump to remove pump variables. OCD. The speedometer is 7% optimistic and most USA bike owners report similar.

I do the same for all the bikes I put miles on. I'm currently getting averaging 42.9 mpg after 10,745 miles, 53 fuel ups. Best tank was 59.4 mpg.

I'm curious about a couple of points that have been brought up in this thread.

1) What is an optimistic odometer? I assume that would be one that indicates something less than actual distance traveled.

2) How can you determine the actual distance between point A and point B? I'd like to assume that a GPS would provide reliable, highly accurate figures for actual distance traveled.

TIA for any meaningful responses.

Don B said:

I'm curious about a couple of points that have been brought up in this thread.

1) What is an optimistic odometer? I assume that would be one that indicates something less than actual distance traveled.

2) How can you determine the actual distance between point A and point B? I'd like to assume that a GPS would provide reliable, highly accurate figures for actual distance traveled.

TIA for any meaningful responses.

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Optimistic is: odometer reports 100 miles but actually traveled only 98.6 miles. GPS is highly accurate. So is cross checking against 50 or 100 miles of interstate mile markers.

Scooter said:

As you can see by this graph, MPG per tank can vary substantially and yet the indicated MPG value calculated by the bike does tend to follow these differences quite closely.

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Nice job tracking every smile! If you were over-the-top anal retentive you would have a description of the riding conditions for each data point

Can't believe you guys put on centerstand to fill! I rarely even get off the bike (unless long trip pit stop), and sometimes don't even shut it off~

I've checked a few times and found the indicated mpg was 2.something mpg less than the actual calculated mpg using mileage from the gps and gallons from the fuel pump. I have never trusted the miles left estimation but I have found the gallons to empty to be consistent and reliable.

The gps is extremely accurate at measuring steady speeds - I've compared it with a patrol car mounted radar unit and found it to be so close as to be indistinguishable. An enduro guy who sets up race courses with calibrated, measured courses says gps's can be off on distance calculations on very twisty turny up and down race courses but he wouldn't give me any exact figures, just that it was off. FYI

Here's my graph for my bike over the first ~60,000 miles:

Actual Trip MPG is odometer mileage divided by fuel added. Same as Scooter, bike is filled the same every time (on center stand).
Dash MPG Gage is average reading for that tank of fuel (it is reset at each fillup).
The pink line is where all points should lie, if everything were perfect.
The black line is the linear regression of where all points actually lie.

On mine you can see that the black and pink lines are not parallel. At high dash indicated mpg, actual mpg is only about 1.5 mpg higher than the dash indicates. At low dash indicated mpg, actual mpg is nearly 3 mpg better than the dash indicates.

Notice how variable some points are relative to actual trip MPG: wind, fuel additives, pump accuracy, fuel quality, and many other factors are involved in the band of blue dots being all over the map.

My MPG indicator is about 7% pessimistic. My speedometer is about 7% optimistic.

Sent from my SM-N920V using Tapatalk

I check mine by mileage every time I fill up and it returns 48 to 55 mpg as a mixed use i.e town and country, the more open road I use the better it is.
Keith.

oslin2012 said:

I check mine by mileage every time I fill up and it returns 48 to 55 mpg...

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Before everyone starts drooling, imperial gallons are 20% larger than U.S. gallons.

--Mark

oslin2012 said:

I check mine by mileage every time I fill up and it returns 48 to 55 mpg as a mixed use i.e town and country, the more open road I use the better it is.
Keith.

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Which is equivalent to 40-46 mpg, US gallon. Typical for low-elevation riding.

In 2014, I got 43 mph (and a few hundreths) over 4500 miles. In 2015, I got 42.2 mph for a bit more than 3000 miles. I tend to ignore the dash indicator because it is calculating the mpg, not measuring it and there have been enough discussions here on the variability of individual bikes and their fuel gages to make me wonder. Fwiw, the dash readout was pretty close in '14 for me, and I think it was significantly lower in '15. Not sure why. Doesn't the readout simply tell you what mileage you got over the last 30 minutes or something like that? It is not the accumulated miles per gallon averaged over the last week, month or year. Right?

Besides, I much prefer the instantaneous mpg - because when i go downhill the mpg goes way up. With no traffic, an empty straight road, and a long downhill, I've even hit 99 mpg with the engine in neutral. (Don't tell me how dangerous this is.)

My gage is pretty close to the one bar = one gallon of gas until it gets below half a tank. I put a speedo healer on the bike and adjusted it to correct the odometer - the speedo now reads between 1 and 2 mph high at 60 to 70.

SMSW said:

In 2014, I got 43 mph (and a few hundreths) over 4500 miles. In 2015, I got 42.2 mph for a bit more than 3000 miles. I tend to ignore the dash indicator because it is calculating the mpg, not measuring it and there have been enough discussions here on the variability of individual bikes and their fuel gages to make me wonder. Fwiw, the dash readout was pretty close in '14 for me, and I think it was significantly lower in '15. Not sure why. Doesn't the readout simply tell you what mileage you got over the last 30 minutes or something like that? It is not the accumulated miles per gallon averaged over the last week, month or year. Right?

Besides, I much prefer the instantaneous mpg - because when i go downhill the mpg goes way up. With no traffic, an empty straight road, and a long downhill, I've even hit 99 mpg with the engine in neutral. (Don't tell me how dangerous this is.)

My gage is pretty close to the one bar = one gallon of gas until it gets below half a tank. I put a speedo healer on the bike and adjusted it to correct the odometer - the speedo now reads between 1 and 2 mph high at 60 to 70.

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I was under the impression that the "average" setting is the tank average since the last clear/reset. Not sure, I guess.
The "instantaneous" readout is pretty much useless as the time delay processing the info makes it far from "instant" and other than a long flat section at perfectly steady speed really tells me nothing.
Some great feedback and info from these posts. If the weather straightens out some I hope to get some miles on and start compiling some of my ow useful data.
Thanks, and keep the results coming.

One other thing to look at - is your temperature guage going reasonably quickly up to 3 bars and staying there regardless of speed? If it takes ages and/or drops down at speed, then your thermostat is likely stuck open, which will affect mpg. Fixing that gave me around an extra 8mpg (going from mid-30s up to mid-40s on reasonably sporty riding, more on easy highway cruising).