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Discussion Starter · #1 ·
So my speed at rest is around 2 MPH off.

It doesn't rest at 0. Wondering if this is all Outbacks or an oddity. If an oddity kind of scared to try and replace it as dashboards never seem to go back together again like they are from factory.

It is consistent. To go 55 I need the speedometer to show 57.5, to go 65 it shows 67.5

Just enough to be mildly irritating lol
 

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2018 White Outback Touring 2.5i
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767 Posts
Did you run a measured mile & time it? Was 62mph actually 60 mph? You can use the green 1/10th mile markers on the side of the highway to double check your actual speed.
 

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2007 2.5 L Obsidian Black Outback XTL
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Have you changed the size of the tires that are on the car?

Taking apart the dash to get to the speedometer is really not the fix. There is a compensation value (a multiplier) that does in to the computer that determines how many pulses from the transmission correlate to a certain velocity. It also will affect your odometer reading.

Usually I would get out on the interstate and set the cruise control and use a stopwatch to count down how long it takes to go exactly ten miles from one roadpost sign to the next. Using a larger number than just 1 mile will increase the accuracy of your measurements.

I get bored on long drives so I do lots of math in my head; for me the habit gets so bad that I could tell you how many alternating white lines were on the pavement between Fort Payne and the Reese City exit on interstate 59. I will count those numbers, then catch the number off of someone's license tag and do long division in my head... Sorry, I am a little autistic about that...
 
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2008 OB Limited 2.5i, Portland OR USA
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There is a compensation value (a multiplier) that [goes] in to the computer that determines how many pulses from the transmission correlate to a certain velocity. It also will affect your odometer reading.
True, but OP said that zero calibration was also off.

I get bored on long drives so I do lots of math in my head; for me the habit gets so bad that I could tell you how many alternating white lines were on the pavement between Fort Payne and the Reese City exit on interstate 59. I will count those numbers, then catch the number off of someone's license tag and do long division in my head... Sorry, I am a little autistic about that...
Nope. Just an engineer. I can spot them a mile off, being similarly afflicted.
 

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2007 2.5 L Obsidian Black Outback XTL
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True, but OP said that zero calibration was also off.
That makes sense that the zero is off, not the span. If it was the span then it would not be a constant offset across two different speeds.
 

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'15 Outback 2.5i Premium
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Just to toss this out there, I found that my Outback's speedometer and odometer were astonishingly accurate, and very slightly pessimistic. In many trips across Arkansas on I-40, I'll reset a trip counter and GPS odometer at mile zero when crossing into Arkansas from Oklahoma, then compare them with the mile posts for the next 270 miles or so to West Memphis (what else are you going to do, especially between LR and Memphis?) The odometer read less than 1.5 miles less than the mile post at the I-55 exit, about 0.5% off, and the GPS distance was closer than that. GPS speed, speedometer reading, and timed distances are also very close, not more than than 1 MPH different in the 70 MPH range.

Tish - I've driven that Ft. Payne to Gadsden stretch of I-59 many times (my brother lives outside FtP now and I grew up in Tuscaloosa, so have friends in the area), but not even I count the stripes, so maybe there's hope for me yet! I do MPG division in my head after filling, though, so I might be doomed after all.
 

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2017 3.6R Limited with Eye Sight
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Could it be the speedometer was calibrated at one latitude and you are driving it at a different latitude, closer to the equator, where the earth's spin is 2 mph faster?

:nerd:
 

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Discussion Starter · #10 ·
Have you changed the size of the tires that are on the car?

Taking apart the dash to get to the speedometer is really not the fix. There is a compensation value (a multiplier) that does in to the computer that determines how many pulses from the transmission correlate to a certain velocity. It also will affect your odometer reading.
It reads 2MPH at totally stopped so tire size isn't an issue. it's 2MPH off if I'm going 5MPH or 100MPH so I don't think it's a multiplier.

And it has the stock tires.
 

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2016 Outback Ltd 2.5 eyesight Nav push button Hole in roof, Lapis Blue
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Also the digital readout is correct.

My radar detector with GPS will read 65, my GPS App (Waze) will show 65, the digital center MID will show 65, and the speedo shows 67 or 67.5
I was going to ask just that... sounds like the needle is just not correctly set on the pin rotating it, if it bothers you that much take it to the dealer but I agree on possibility of a clip or 2 being broken or just not hold as tight as before... talk it all over with the service dept.

#subaruambassadors
 

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[geezer]When I started driving, if a speedometer was within a few miles per hour of correct I'd have been astonished! Many of them were 5 to 10% off. Always optimistic.[/geezer]
 

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Well, at least pre-digital, the discrepancy wouldn't be considered unusual, at least as it was several years back. The industry standard is or was within 4% between speedo and actual speed. For example, my 1999's (replacement) speedo consistently shows two mph above what street electronic speed indicators do ("Your Speed"), for example 27 shows as 25 on the street.
 

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Well, at least pre-digital, the discrepancy wouldn't be considered unusual, at least as it was several years back. The industry standard is or was within 4% between speedo and actual speed. For example, my 1999's (replacement) speedo consistently shows two mph above what street electronic speed indicators do ("Your Speed"), for example 27 shows as 25 on the street.
27 indicated when you're really going 25 is 8% optimistic (27/25 = 1.08, or 8% high.) This matches my experience.
 

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27 indicated when you're really going 25 is 8% optimistic (27/25 = 1.08, or 8% high.) This matches my experience.
I was thinking after I posted maybe it was up to 4 mph off, not 4%. Checking now, federal rules say "reasonable accuracy," which they interpret as plus or minus 5 mph at 50 - https://www.fmcsa.dot.gov/regulations/title49/section/393.82

I've always assumed but have never been able to test that if it's off 2 mph at 25, then at 50 or 60, it'd be off maybe 4-5 mph. I've also assumed that the speedometer and odometer don't match. Is that true? I mention it because using the highway mileage markers, my trip odometer, i.e., with tenths, has always been off a little.
 

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My experience has been that the % off doesn't follow with higher speeds. Once it reaches 3-4 MPH off, it seems to stay about the same, regardless of increased speed. Especially with analog gauges, that seems strange. But I know I've had cars that were several MPH off at low speed (around 30) and remained about the same MPH difference at freeway speeds.
 
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