Are car fuel consumption computer accurate
Discussion
Roo said:
The one in the Prius over reads by about 10%. As does the speedo and mileometer.
I suspect this is where most the inaccuracies come from. Speedos (for safetys sake ) always over-read so the user is not in danger of breaking speed limits. I would suggest that this means the consumption computer always 'thinks' a greater distance has been travelled (assuming it uses the same data source) and therefore gives a better MPG figure.....Mike
It's conceivable that the algorithm being used by some cars to calculate the displayed "average" fuel consumption is doing something other than adding up fuel injected and dividing by miles travelled since last reset.
Edit - reciprocal, obviously.
Edit - reciprocal, obviously.
Edited by otolith on Saturday 18th August 13:33
Roo said:
The one in my Mustang is extremely accurate based on mileage between fill ups etc.
The one in the Prius over reads by about 10%. As does the speedo and mileometer.
I find this with the 'Stang too, but then if like other posters have said that speedo accuracy comes into it then that might be why, I find that when comparing to the GPS speed measurement the 'Stangs speedometer is saying 70 when the GPS is saying 69.The one in the Prius over reads by about 10%. As does the speedo and mileometer.
kambites said:
Always struck me as odd that people are intensely distrustful of their ECU's MPG reading, let trust the odometer when doing manual calculations.
Haven't people "read" the speed at the OBII port and seen it matches the sat nav while the speedo is showing 10% higher. The Odometer would be odd if it miss read by as much as distances between motorway junctions etc would soon show it up, print off a route plan then compare the route and your mileage.PanzerCommander said:
I find this with the 'Stang too, but then if like other posters have said that speedo accuracy comes into it then that might be why, I find that when comparing to the GPS speed measurement the 'Stangs speedometer is saying 70 when the GPS is saying 69.
They do seem to be incredibly accurate. Must be an American thing as they all seem to be like it.I have an iPhone app that records mpg on each fill up.
Interestingly my last SLK (2005) was about 10% optimistic, whereas my current one (2009) is absolutely bang on.
Good comments about accuracy of milometer, but checking speedo against GPS it's very close, so be surprised if mileage wasn't given that presumably they use the sane data.
Interestingly my last SLK (2005) was about 10% optimistic, whereas my current one (2009) is absolutely bang on.
Good comments about accuracy of milometer, but checking speedo against GPS it's very close, so be surprised if mileage wasn't given that presumably they use the sane data.
Engineer1 said:
kambites said:
Always struck me as odd that people are intensely distrustful of their ECU's MPG reading, let trust the odometer when doing manual calculations.
Haven't people "read" the speed at the OBII port and seen it matches the sat nav while the speedo is showing 10% higher. The Odometer would be odd if it miss read by as much as distances between motorway junctions etc would soon show it up, print off a route plan then compare the route and your mileage.Gassing Station | General Gassing | Top of Page | What's New | My Stuff