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12-20-2012, 03:49 PM | #1 |
Scooby Newbie
Member#: 208409
Join Date: Apr 2009
Chapter/Region:
Tri-State
Location: NJ
Vehicle:2012 WRX Sedan WRB |
Speedometer/Odometer Question
My speedometer is off, according to my Garmin GPS and an app that uses GPS to track distance traveled over time. When my car's speedometer says 84, I'm actually only traveling 80. 53mph on the dash is only 50mph according to GPS, so naturally I became curious. My questions are:
1. Does the odometer feed off speedometer's reading? If so, were I to travel 80mph (according to GPS) for one hour, would I actually have put 83 miles on my car's odometer? 2. How does the odometer work? If I put bigger tires on the car, would I actually travel farther than my odometer would have me believe? The vehicle in question is a 2006 Subaru Impreza 2.5i. Thanks for any and all help. And please pardon my NASIOC naivete if this is in the wrong section.
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12-20-2012, 03:54 PM | #2 |
Scooby Newbie
Member#: 273214
Join Date: Feb 2011
Chapter/Region:
MWSOC
Location: Columbus,OH
Vehicle:2013 WRX Limited CBP |
If you are running different sized tires from stock than you can expect your speedometer to be off a little bit. I am sure this is the same for your odometer.
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12-20-2012, 03:57 PM | #3 |
Scooby Newbie
Member#: 329284
Join Date: Aug 2012
Chapter/Region:
NWIC
Location: Eugene, Oregon
Vehicle:02 WRX Sport Wagon Aspen White |
Just thought I'd throw in a quick note that different tires/tire pressure and all the little calculations can make it be off. I'm not sure if your familiar with mightycarmods but there was a YouTube video explaining it as well as a speedometer correcting device. It would be a pain to wire/not even worth it but it explains it all.
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12-20-2012, 04:15 PM | #4 |
Scooby Newbie
Member#: 208409
Join Date: Apr 2009
Chapter/Region:
Tri-State
Location: NJ
Vehicle:2012 WRX Sedan WRB |
So the odometer is dependent on the speedometer's reading, is that correct?
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12-20-2012, 07:07 PM | #5 |
Scooby Newbie
Member#: 224197
Join Date: Sep 2009
Chapter/Region:
NESIC
Vehicle:2015 435ix GC Imperial Blue |
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12-20-2012, 07:09 PM | #6 |
Scooby Newbie
Member#: 333203
Join Date: Sep 2012
Chapter/Region:
SCIC
Location: Southern California
Vehicle:2012 Sport Premium MBP 5 SPD |
I'm pretty sure the answer is no. I am basing that off the fact that in most cars, if the speedometer were to not work for some reason, the odometer should still continue to function. If the odometer were dependent on the speedometer, then when the speedometer is not functioning, the odometer should not function as well.
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12-21-2012, 10:30 AM | #7 |
Scooby Guru
Member#: 118209
Join Date: Jun 2006
Chapter/Region:
MWSOC
Location: North Dakota
Vehicle:2015 WRX Limitec |
They both read the VSS wire from the trans... So if your speedo quits, the odometer may or may not also quit incrementing, depending on what caused the problem in the first place. (failed stepper motor in the speedo, odo keeps working. failed VSS signal for any reason, they both go dead.)
And yes, having an incorrect speedo because of gearing/tire changes also means the odo will read incorrect. |
12-21-2012, 02:47 PM | #8 |
Scooby Specialist
Member#: 234363
Join Date: Jan 2010
Chapter/Region:
TXIC
Location: Beaumont
Vehicle:2015 Katie Em 250 XC Dirty bike |
I'm also pretty sure all cars come from the factory to read a little high. It gives them a cushion zone, so when you are going the speed limit you are actually under and won't get a ticket. My 06 Sti and 05 mini both do the same thing and by the same amount as yours. As far as if your odometer is reading actual mileage I do not know. I would assume it counts tire rotations times circumference of a stock sized tire. While your speedo can have the computer tell it to read 4% higher than what it's calculating.
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12-29-2012, 09:56 PM | #9 |
Scooby Newbie
Member#: 208409
Join Date: Apr 2009
Chapter/Region:
Tri-State
Location: NJ
Vehicle:2012 WRX Sedan WRB |
Thanks for all the answers. The last two were especially informative. Thanks again!
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12-29-2012, 11:24 PM | #10 |
Scooby Guru
Member#: 72891
Join Date: Oct 2004
Chapter/Region:
MAIC
Location: In the blue & hating it!
Vehicle:2018 STI 99 2.5RS 2dr - 2017 XV |
Subarus are about 3%-5% off on average. They read faster than your actual speed. There was a class action suit about this issue where Subaru agreed to extend warrenty claims MY 02-07.
" Subaru of America, Inc. will extend by 5% the mileage-based coverage periods of certain warranties, extend annual mileage allowed by vehicles leased from Subaru Auto Leasing, Ltd. by 5%, and reimburse certain repairs and excess mileage charges." http://classactionlawsuitsinthenews....ction-lawsuit/ |
12-30-2012, 09:59 AM | #11 | |
Scooby Specialist
Member#: 132952
Join Date: Nov 2006
Chapter/Region:
MAIC
Location: Delaware
Vehicle:2005 Impreza WRX STi Black |
Quote:
Mike K |
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12-30-2012, 10:14 AM | #12 |
Scooby Newbie
Member#: 333820
Join Date: Sep 2012
Chapter/Region:
South East
Location: Miami
Vehicle:2013 WRX Limited WRB |
On my 2013 gauge and GPS is dead accurate at 75mph
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12-30-2012, 10:26 AM | #13 |
Scooby Guru
Member#: 72891
Join Date: Oct 2004
Chapter/Region:
MAIC
Location: In the blue & hating it!
Vehicle:2018 STI 99 2.5RS 2dr - 2017 XV |
My 96 and 04 both read fast. My 04 is dead accurate with 235-40-18 tires but with stock size it reads 3 mph fast at 60 mph. I have to add that every car I have owned read fast according to my GPS and the speed warning sign on the side of the road. Average on both my Fords is 2 mph fast.
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12-30-2012, 11:16 AM | #14 |
Scooby Newbie
Member#: 318428
Join Date: Apr 2012
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Every car I own reads fast as programmed by the manufacturer. No big deal I'd rather it read fast and save me a ticket than the other way around. The speed limit is a maximum speed not a target speed so if someone yells at you over driving 4 mph under the speed limit that is their issue not yours....
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12-31-2012, 06:00 PM | #15 |
Scooby Specialist
Member#: 81995
Join Date: Feb 2005
Chapter/Region:
BAIC
Location: San Francisco
Vehicle:2022 FORESTER SPORT 02 WRX 247k RIP |
yeah mine reads about 3 mph fast at freeway speeds. and i've always had stock size tires since i bought the car.
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