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Discussion Starter #1
Observation:

My speedo reads 60 but my scangauge II says 57 - which is accurate? Neither?

Wondering where the scangauge gets it's info from - obviously not the same place the speedo gets it from.

Anybody experienced this or have any input?
 

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Speedometers are not always 100% accurate. I had the same thing with my old GTI. A GPS would always read 2-3 mph. The higher a speedometer reads to, the greater tolerance it is allowed to have. Ours goes to 180, so it can be less accurate than other cars. Also, they tend read higher than lower, but at least this (kinda) prevents tickets (not really).
 

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Haven't tryed the Scangauge II, but was curious as to how it compares to the AE scantool. I've heard alot of stock speedometers can be slightly off, but I've never done any real tests. I know that if I drive by one of those radar readouts on the side of the road, my speedometer reads a few blow the one on the street, but who's to say how accurate that police equipment is.
 

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I've noticed the 2-3mph higher reading on my speedometer in all of my previous vehicles. Its normal, I actually like it, as mtx said, it helps with tickets in a way.
 

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Well as far as the police and the speed signs... doesn't really matter how "accurate" they are.... if the speed they pick up = ticket... you get a ticket.. .sadly...

NOW.. if your going 50 in a 45.. .and the cops device says 150 mph... you could probably fight it...

HOWEVER a good friend of mine got a ticket for 85 in a 65... when his speedo was showing 79 or something... AND... i was in my civic which was reading around 80ish as well... cops device was off IMO... but hard to prove / fight...

:EDIT:

Also... i don't get a chance to test my speedo vs those speed-signs... because when I see em (or my rador picks them up so i know its comming) I always drop a gear and jam on the gass.... its fun to see it read 55...60..55...60 as other cars pass.. then 90... as i fly by =)
 

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Discussion Starter #6
Well as far as the police and the speed signs... doesn't really matter how "accurate" they are.... if the speed they pick up = ticket... you get a ticket.. .sadly...

NOW.. if your going 50 in a 45.. .and the cops device says 150 mph... you could probably fight it...

HOWEVER a good friend of mine got a ticket for 85 in a 65... when his speedo was showing 79 or something... AND... i was in my civic which was reading around 80ish as well... cops device was off IMO... but hard to prove / fight...

:EDIT:

Also... i don't get a chance to test my speedo vs those speed-signs... because when I see em (or my rador picks them up so i know its comming) I always drop a gear and jam on the gass.... its fun to see it read 55...60..55...60 as other cars pass.. then 90... as i fly by =)
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Gotta make it show the "00" !!!

Tomorrow I'm going to bring my GPS and see how far off both the speedo and scangauge are - under the assumption that GPS is the most accurate.
 

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OEM speedos have an error/tolerance during manufacturing, so to protect themselves a lot of OEM speedos show a bit higher speed. Best way to know for sure is borrow a handheld GPS and compare.
 

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I have the Scangauge II and a GPS. With the stock tires all devices agree perfectly--speedo, Scangauge, GPS. With the 225/45/18's I have on for winter I find the speedo/Scangauge read at least 1 MPH too slow from about 60 up.

By the way--LOVE the Scangauge II :love:
 

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when I see em (or my rador picks them up so i know its comming) I always drop a gear and jam on the gass.... its fun to see it read 55...60..55...60 as other cars pass.. then 90... as i fly by =)
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I thought I was the only one who pushed it up a bit to get a higher reading... Never anything close to 00 as someone posted...

I think all cars +/- 5mph on their speedos but they will be more accurate at certain speeds.
Like you may be off by 3mph+/- at 40mph but at 70 you maybe + 5mph.

I believe this is part of the reason most cops will give a 10mph over "free pass" before they write you a ticket, although can legally write you a ticket for 1mile over.
 

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my car is about 2-4% optomistic with the stock tire config. By handheld GPS I'll be traveling a true 58 The speedo in the car will be dead on the 60mph line.
 
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