Honda drivers, are you accounting for the inflated odometer reading in your MPG?
 

This should be a lively topic. I've often thought about this and never notice anyone mention it in their mileage calculations. Honda has been sued over their bogus odometer readings, I believe more than once. I recall a warranty extension for millions of cars. I know my 95 Accord reads conveniently high. Not the quite the 4% of some Honda's but still too much. This issue applies to some Nissan/Infiniti vehicles as well. I know no one likes getting lower mpg but I think we all appreciate accuracy.

In my 98 Civic, the speedo is off, yet the odometer is right on the money in factory form. Since I have over sized tires, I have to add 5% distance to my MPG calculations, but it corrected the factory speedometer to GPS indicated speed.

I originally believed that since my speedometer was indicating the GPS speed, my odometer must be accurate. Guess not!

That's a twist, I expected the two to be in sync. I better check my OD now.

It's not only Hondas, I found similar inaccuracy with my Mazda.

On standard size tyres, the speedo reads fast & the odo reads slow (compared to my GPS).

On the taller tyres I run now, the speedo is correct and I multiply the odo readings by 1.057 when calculating my MPG.

My Honda is 23 years old, I would think that any issues it came with have only been made worse over the years. But for me, since I don't use GPS or any other instrumentation to verify my results, I am not super concerned with the accuracy of the odometer. Maybe I avg 37 mpg, maybe in reality it's 34? The part that interests me is the improvement I can make in whatever number I am getting. I am assuming that any issues with accuracy are at least consistent issues (ie being off a few percent when new compounded with years of wear), so as long as everything stays at the same level of broken then I can at least track my improvements! :snail:

I don't have a Honda but I do have to make an odometer correction.
I have checked my odometer against mile markers and GPS, averaged the difference (less than 1% between the 2 methods) and figured I have to add 3% to my suburban odometer mileage.
Found out recently that is because some time in the past the 3.08 rear end that my suburban left the factory came with was swapped for a 3.42 unit.

I checked my odometer against a GPS and I have to adjust my mileage. My odometer is actually underreporting due to the size of my tires.

My odometer is underreporting by at least 1%.
Yesterday I took a trip that both Google and my TomTom said would be 83.1 km long.
Ended up @ 82 km dead on the driveway.
I see the same pattern on my commute: the odometer reports about 0.5 km less than the GPS shows for 36 km.

Car has the original 185/55/R16 tires for 15,000 km. Same with the 175/65/R15 winter tires.

I did add liters to my fuel log for using a fuel pump that is off. Should I now also add some kms for my underreading odometer?
When precision and vanity go hand in hand, should I give in? ;)

In Washington state, there are a bunch of odometer check stations on the freeway. Five miles, precisely marked off in one mile increments. Based on that I know my odometer is 1% or less off in my '01 Civic. That's close enough for me.

1% is 1% :turtle:

I'd add it. :)

I'm adding 3.4% due to larger tyres, but I really should check the odometer against GPS / kilometre signposts.

In my experience though,
speed is always overreported
(as legally they may not show you're going slower than you actually are)
odometer OTOH is quite correct


In the up! , the speedo even shows a different speed than the digital speed readout buried in the OBC ! :rolleyes:
Speedo indicates highest.
OBC reports a few kph less than speedo.
GPS reports yet another few kph less than OBC ...
And that's even despite the tires being too large!

I just check the odo readings on my normal weekday trip which is 39.8 miles round trip. This is a camparison of probably every vehicle average in my garage, something like 16 different vehicles.
The truck reads low since I put larger tires on it, so I correct it by 1.026 to get the true distance.
Occasionally they put one of those radar machines on the side of the road and I'll check the speedometer against the radar. The truck and Fiesta are spot on, need to check the bikes, since they are supposed to be optomistic.

regards
Mech

My car currently understates miles by about 5.5%... checked it repeatedly with a GPS unit and ridewithgps.com

My old Civic was almost exactly right with new tires. With worn tires it overreported by about 2%. My Fit underreports by a little.

My 2004 Odyssey is one of the ones in the class-action lawsuit. It DOES overreport by about 5%.

The difference between new tires and worn tires is approximately 2% (new is typically 10/32" tread depth, 2/32" is worn = 8/32" difference. Times two for tread on top and bottom is 1/2" on a 26" tire for 2%). Do you factor that in as well?

I've seen a wide range on my motorcycles. The worst in my Kawasaki 650R, the odometer reads very close (within 1%) but my speed reports 10% higher than actual! (checked using GPS, radar machines, and odometer check points). Most of my bikes have been 3-5% off on the speedo with the odometer being far more accurate.

Oh good, i thought there was something wrong with my brand new car's digital odometer.

Odo seems to be underreporting by 3% when compared to my gps.

Another thought, does a GPS take grades into account when you use it for distance measurement?

Yes.