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'02 Bean H6, AWP & ORP, factory hitch
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Discussion Starter #1
I'm rarely in a hurry to get anywhere (most times just leave early) but I have noticed that while going an indicated 75mph on the interstate, for example, I'm getting blown away by all other traffic. Decided to experiment. Got on the interstate one day and loaded a GPS app I have on my phone. Wow! According to my GPS, to go 70mph I have to go a speedo indicated 82mph!!! So I also tried timing myself with mile marker signs. Granted, they are probably nowhere near perfect, but in between mile markers, my odometer consistently shows 1.2 miles. I'm really intrigued now. So I ran a series of tests at different speeds, and according to 2 different GPS programs, the speedo is wrong. The faster I go, the bigger the discrepancy. At an indicated 50mph, GPS says 45. I could accept that problem as a nuisance, but realized that my odo turns 1.2 mi for every GPS indicated mile. So I ask myself, how many miles does the car REALLY have on it? I have Conti ProContact on all 4 corners, religiously rotated and nitrogen-filled. They have about 25k on them and tread depth is equal to 1/32 on all 4. So, what the ****? Speedo I really don't care about, but the odometer is incorrect. Actual mileage is now less than what the odo reads. Anybody else experienced this?
 

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03 H6 OBW & 06 WRX Sportwagon
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17,704 Posts
I seem to recall Subaru got in some trouble about this in the past?

also, are the tires the correct size as listed for the car?
 

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2004 Outback L.L. Bean
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25 Posts
I also noticed the same thing on my 04 Beaner, but not as much discrepancy. Mine reads 4-5 mph low at 75 according to multiple GPS comparisons.
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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4,112 Posts
My 2011 Sonata is 3 mph off. I went on a Sonata site and folks were saying a bunch of crap about how manufacturers made them appear faster so folks wouldn't drive as fast. WTF? I tested my Subaru and it is about half a mph off and my Suburban is about .75 of a mph off. They are both over 10 years old and I'd expect some lag over time. But 2011?

None of the sites I've been to suggested a fix for the problem. I wonder how much warranty I'll loose with the difference in mileage? I feel your pain.
 

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2007 OBXT Limited, 5MT 148K
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420 Posts
I also noticed the same thing on my 04 Beaner, but not as much discrepancy. Mine reads 4-5 mph low at 75 according to multiple GPS comparisons.
Unlike the OP's reading, this is actually considered acceptable. US DOT requires the speedometer reading to be with 5mph (+ or -) when the vehicle speed is 50mph.
 

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03 H6 OBW & 06 WRX Sportwagon
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17,704 Posts
Unlike the OP's reading, this is actually considered acceptable. US DOT requires the speedometer reading to be with 5mph (+ or -) when the vehicle speed is 50mph.

whoa - 10% !

that seems like a lot. I could see 3% 'as delivered' - but 10 seems crazy.
 

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2013 Legacy Lim CVT Car: 2011 OB Prem 6MT Car: 2006 Miata GT 6MT mc: 2003 Honda GL1800A * Reunite Gondwanaland *
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3,567 Posts
Conti ProContact on all 4 corners, religiously rotated and nitrogen-filled.
There's your problem -- shoulda used argon. :2:

...OTOH, your mpg "improved" by 10%,

Looby
 

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'02 Bean H6, AWP & ORP, factory hitch
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Discussion Starter #14
Not that I plan on selling it, but it's rolling up some serious miles driven that don't exist. Also, since the problem is now an algorithm that prevents me from determining my fuel mileage.
 

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03 H6 OBW & 06 WRX Sportwagon
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I've had good results using a 78% nitrogen fill for decades.
 

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2005 Legacy 2.5i Wagon 4EAT; 2005 Forester XS 4EAT
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672 Posts
This is probably my biggest complaint with my Subaru. Odometer reads 74(ish) when I'm really going 70. Also, if the PCM is anything near that inaccurate, that means mine shouldn't have anywhere near 234,000 miles on it. If it's 5% off, that means mine really has 222,000 on it. That's a difference of nearly 12,000 miles.
 

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'02 Bean H6, AWP & ORP, factory hitch
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3,113 Posts
Discussion Starter #19
This is probably my biggest complaint with my Subaru. Odometer reads 74(ish) when I'm really going 70. Also, if the PCM is anything near that inaccurate, that means mine shouldn't have anywhere near 234,000 miles on it. If it's 5% off, that means mine really has 222,000 on it. That's a difference of nearly 12,000 miles.


I hear ya. I could just see me selling it..."But really, it only has 155k mi. Don't worry about the odo reading sir! I promise.....
 

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'02 Bean H6, AWP & ORP, factory hitch
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3,113 Posts
Discussion Starter #20
It would be pretty uncomfortable for me cruising the interstate with the cruise set on 85mph and going by a state trooper!!!
 
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