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Accuracy of Mileage Computer..?


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Has anyone compared the trip computer's gas mileage readings to what they've calculated via the odometer and/or GPS versus amount of gas filled?  Per tank?  How about over time?

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It will be out slightly as speedo isn't accurate.  Also will alter depending on how much throttle is used and which gear. 

 

In short no. 

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4 hours ago, fink said:

It will be out slightly as speedo isn't accurate.  Also will alter depending on how much throttle is used and which gear. 

In short no. 

 

Actually I've found the speedo on my 2014 to be unusually accurate.  And historically I've found that even on bikes where the speedo was a good 10% on the high side, the odometer was still fairly accurate.  So this conjecture doesn't really fit with my experience.

 

In addition, my last tank of gas - half city and half highway - showed results that were remarkably close to the indication on the trip computer.  Given some variability of what constitutes a "full" tank, a better test would involve tracking several tank-loads of gasoline but it did get me curious.

 

I'll await more answers from folks with actual experience.  ;-)

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More importantly, what MPG does it say you are getting ?

You will be hard pressed to get better than around 40mpg (UK gallon @ 4.5L/gallon) if you use the throttle as intended.

on my Trackday last week I got 60miles on half a tank, so estimate that was around 25mpg, when in normal use I get about 38mpg.

 

Riders in the USA that get 45+mpg (US gallon=approx 3.8L) should trade it in for a Cruiser or learn how to ride it ! :) 

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The speedometers on the 8th gens. were changed to be dead on correct.  Previous gens. were known to read 10% fast.  My odometer is correct too.  The speedo takes a little getting used to since it doesn't lie any more like my previous 5th and 6th gens.  That really didn't matter since I can only ride to whatever my capabilities are if I choose to do that.  

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8 hours ago, Mohawk said:

More importantly, what MPG does it say you are getting ?

You will be hard pressed to get better than around 40mpg (UK gallon @ 4.5L/gallon) if you use the throttle as intended.

on my Trackday last week I got 60miles on half a tank, so estimate that was around 25mpg, when in normal use I get about 38mpg.

 

Riders in the USA that get 45+mpg (US gallon=approx 3.8L) should trade it in for a Cruiser or learn how to ride it ! :) 

 

There are other discussions about mileage experience on this forum.  It is not necessary to repeat that here, not would it be consistent with the topic.

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I tracked MPG manually for a while and found it to be pretty accurate.  Actual speed seems accurate, too.  I didn't check speed formally with GPS or anything, but the radar warnings that I pass from time to time seem to agree with my indicated speed.

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6 hours ago, Bent said:

The speedometers on the 8th gens. were changed to be dead on correct.  Previous gens. were known to read 10% fast.  My odometer is correct too.  The speedo takes a little getting used to since it doesn't lie any more like my previous 5th and 6th gens.  That really didn't matter since I can only ride to whatever my capabilities are if I choose to do that.  

The speedos are slightly out.  I posted up a few months ago. 

 

Will check again tomorrow to see what readings I am getting as I mostly ride with sat nav attached.   

At  an indicated 70, gps reads about 66mph. 

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35 minutes ago, fink said:

The speedos are slightly out.  I posted up a few months ago. 

 

Will check again tomorrow to see what readings I am getting as I mostly ride with sat nav attached.   

At  an indicated 70, gps reads about 66mph. 

 

Yours must be out.  Mine isn't with a GPS.  Numerous road reviews have also stated the 8th gen. speedometer is correct too.    

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Road reviews also state a number of other things which aren't also correct. I can remember one saying the fjr had 6 gears.  It only has 5  ( well up until the release of this years model ). 

 

Have you run gps against your speedo?

 

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2 hours ago, fink said:

Road reviews also state a number of other things which aren't also correct. I can remember one saying the fjr had 6 gears.  It only has 5  ( well up until the release of this years model ). 

 

Have you run gps against your speedo?

 

 

Requoted:   "Mine isn't with a GPS."  Period. End of discussion.  

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2 hours ago, Bent said:

 

Requoted:   "Mine isn't with a GPS."  Period. End of discussion.  

Touchy indeed. 

 

For those that are interested. 

 

30 =30gps

60= 58 gps

70= 68gps

80= 77gps

90= 87 gps

 

ave mpg today is sitting at 49.9 mpg so far. 

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my Gen 8 speedometer was consistently within 1 MPH of GPS, and by GPS I mean compared to a Samsung 7 inch tablet running CoPilot software. So this helps back up other's results, independent of comparisons to Garmin devices.

 

I do not think I checked this above 75 MPH though.

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My speedo and mileometer are 5% out compared with a GPS. I also compared this with a Ducati 1098 over a 2500 mile trip and I did 5% more than was indicated by him and we did exactly the same journey. So at 80MPH GPS was showing 76MPH etc

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  • 1 month later...

It probably depends on which version you have. European Honda motorbikes add 6% because of legislation like in my country where speedos must never display less than the actual speed.
US versions of many other vehicles are known not to add anything.

 

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I have checked my 2014 VFR800FD speedometer multiple times with a GPS app on my Iphone (its my GPS on the bike), both read exactly the same speed every time I compare them. Ive compared the same Iphone app in my Toyota 4runner and in my Acura with my Garmin GPS to compare for any differences. The Iphone and Gamin are reading the same speeds and distances. I have not compared the speedometer reading to the app above 90. My average MPG is 38.2, maybe I will reset it since I dont think I ever have, and see what the difference is.

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  • 1 month later...
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Update...  I tracked indicated trip odometer mileage, indicated MPG and gallons filled, computed the MPG and averaged the results over 1610.1 miles of combined city and highway riding and nine fill-ups to even out variations due to the inevitable inconsistencies in fill-ups.  I got an average error in indicated gas mileage of -0.23 MPG compared to computed mileage.  I think that's pretty good!  Smallest deviation over the fill-ups was 0.039 MPG and the largest was -1.985.

 

Also, I took a fifty mile ride on the Long Island Expressway today and compared the odometer to my GPS, and found the odometer reading to be about 1% greater than the GPS reading.  I am not near a straight enough stretch of road to make a useful comparison to road markers.  The 1% optimism seems to be roughly comparable to the speedometer's accuracy as compared to the same GPS (Garmin Zumo 665).

 

My rear tire was a few pounds low but if the odometer readings are taken from the front wheel that should not have induced any errors.

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On ‎24‎/‎07‎/‎2016 at 10:04 AM, Rectaltronics said:

Has anyone compared the trip computer's gas mileage readings to what they've calculated via the odometer and/or GPS versus amount of gas filled?  Per tank?  How about over time?

 

Here's a couple of trips done that I've logged - sorry its metric! But it still shows the indicated average fuel useage to be pretty accurate.

 

Distance = 407K's, Fuel Used 16.05litres, Instrument Gauge Read 3.9Litres/100k's, Calculated = 3.94Litres/100k's ( best fuel run I've done on standard unleaded 91ron also included some hills and twisty bits )

Distance = 403K's, Fuel Used 17.48litres, Instrument Gauge Read 4.3Litres/100k's, Calculated = 4.34Litres/100k's

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Thanks Grum.

 

FYI the reason I wanted to average over a number of fill-ups is because I'm quite certain that I don't consistently fill the gas tank to the same level each time.

 

But yeah, the accuracy seems pretty decent to me.

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