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Odometer Accuracy: 2016 Outback

2K views 8 replies 7 participants last post by  Bluebird 
#1 ·
My 2016 Outback, a 3.6, has 3,500 miles on it. Or so says the odometer. In fact I've driven about 3,600 miles. The odometer undercounts distance by a touch less than 3 percent.

I've tested and retested this. My calculation is correct. Is a 2.5 to 3 percent undercounting error within the range of normal on this car? It doesn't seem right to me.

I realize that this error could give me a slight advantage at resale but I don't like it. Have others experienced error of this kind? Do you have advice?

In case it's relevant, I haven't made any modifications to the car. I love the car but I'm curious about this.
 
#2 ·
I'm surprised by this. I tested the displayed digital speed against a WAAS GPS and it is spot on, which is unusual in cars in my experience--they usually read two or three mph higher than actual speed. But the conversion to accumulated mileage is another matter. I'm wondering how you measured miles traveled.
 
#5 ·
I wouldn't be surprised at a ~3% deviation - I've heard for a long time that speedometers & odometers are not super accurate. Even if they are perfectly reliable, things like tread depth, tire inflation and even temperature can account for incorrect readings.

I just read a few posts about the SAE and EU standards (US regulation is surprisingly vague so MFGs seem to shoot for the EU standards) which state they should never be low but can read up to 5% high - therefore the manufacturers tend to calibrate on the high side to comply with the "never lower" best practice. But there are two notes - that percentage does not take into account tire variations and the % is of total indicated speed, so if you have a 150MPH speedometer you're speedometer can be off by 7.5MPH and still be considered compliant regardless of true speed. I guess that is why they always seem to put impossibly high top speeds on there... I don't think I could get my OB to hit 150 even if I dropped it out of a plane.
 
#6 ·
Much to my surprise, both my speedometer and odometer read slightly low compared to GPS-determined speed and distance by about 0.5%. GPS distance agrees with the Oklahoma and Arkansas highway mileposts to within 0.1 mile (the resolution of the GPS odometer display) over 70 miles and 270 miles, respectively. As far as I know, those milepost locations are surveyed, so I presume they're accurate over long distances.
 
#7 ·
Mine is about 1.5% off....on the low side. calibrated with various GPS (not the one in the car navigation) and known distances.
Don't know why they can't get this right.... Use the GPS 99% of the time when it has a signal and revert to the old innacurate method in the rare instances you don't have a GPS signal. This would make it 99.9% accurate. Not exactly rocket science.
 
#8 ·
You know, the man with 2 watches never really knows what time it is.
 
#9 ·
Thanks for all the replies. In answer to the question of how I know the odometer runs 2.5 - 3 percent low: Two methods.

(1) Highway mileposts, which I assume are accurate.

(2) I have a cottage that's exactly 300 miles from home, or used to be. I've driven there 50 times in different cars always following the same route. All of a sudden it's only 292 miles away!
 
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