MPH Discrepancies

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hmatiak
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MPH Discrepancies

Postby hmatiak » Sun May 30, 2010 12:50 am

A on going issue with my last two Nissans. Bought a '07 Xterra brand new and put our GPS on the dash. At highway speeds the speedo was 2-3 mpg off. After having it checked by the dealer and them finding nothing i tested with another gps, same thing, still off. The problem was only solved by going up a tires size, 265/75/16.

Having the same issue with the new Pathfinder. Speedo is off the same amount. I know of several other Pathfinder/Xterra owners with the same issue when running stock or stock sized tires. The only exception is the Off-Road models of both, with the one size larger tires.

Im sure this could be applied across the board with Nissan vehicles, more so the truck based versions.

Currently Honda has a lawsuit against them for the same infraction. The speedometer reads faster than you are actually traveling. Racking up miles faster and sooner than if it were not reading 2-3 MPH faster than it should be. Putting you out of warranty coverage sooner than it should.

The slower the speed the less of a deviation, the faster the more. 3 MPH difference is at 75-80 MPH.

Just some info to pass along, and dont doubt the accuracy of your GPS. They have been proven to be more accurate than people will give them credit for when displaying MPH.


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disallow
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Re: MPH Discrepancies

Postby disallow » Sun May 30, 2010 7:18 am

hmatiak wrote:A on going issue with my last two Nissans. Bought a '07 Xterra brand new and put our GPS on the dash. At highway speeds the speedo was 2-3 mpg off. After having it checked by the dealer and them finding nothing i tested with another gps, same thing, still off. The problem was only solved by going up a tires size, 265/75/16.

Having the same issue with the new Pathfinder. Speedo is off the same amount. I know of several other Pathfinder/Xterra owners with the same issue when running stock or stock sized tires. The only exception is the Off-Road models of both, with the one size larger tires.

Im sure this could be applied across the board with Nissan vehicles, more so the truck based versions.

Currently Honda has a lawsuit against them for the same infraction. The speedometer reads faster than you are actually traveling. Racking up miles faster and sooner than if it were not reading 2-3 MPH faster than it should be. Putting you out of warranty coverage sooner than it should.

The slower the speed the less of a deviation, the faster the more. 3 MPH difference is at 75-80 MPH.

Just some info to pass along, and dont doubt the accuracy of your GPS. They have been proven to be more accurate than people will give them credit for when displaying MPH.
If I'm not mistaken, there is an allowable % they use to set the speedo. Helps people not get speeding tickets...

Also, in my opinion, warranty should be based on engine hours, not distance. If it were, this issue wouldn't matter, and warranty would be based on a more measurable and objective thing.

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hmatiak
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Re: MPH Discrepancies

Postby hmatiak » Sun May 30, 2010 5:36 pm

disallow wrote:
hmatiak wrote:A on going issue with my last two Nissans. Bought a '07 Xterra brand new and put our GPS on the dash. At highway speeds the speedo was 2-3 mpg off. After having it checked by the dealer and them finding nothing i tested with another gps, same thing, still off. The problem was only solved by going up a tires size, 265/75/16.

Having the same issue with the new Pathfinder. Speedo is off the same amount. I know of several other Pathfinder/Xterra owners with the same issue when running stock or stock sized tires. The only exception is the Off-Road models of both, with the one size larger tires.

Im sure this could be applied across the board with Nissan vehicles, more so the truck based versions.

Currently Honda has a lawsuit against them for the same infraction. The speedometer reads faster than you are actually traveling. Racking up miles faster and sooner than if it were not reading 2-3 MPH faster than it should be. Putting you out of warranty coverage sooner than it should.

The slower the speed the less of a deviation, the faster the more. 3 MPH difference is at 75-80 MPH.

Just some info to pass along, and dont doubt the accuracy of your GPS. They have been proven to be more accurate than people will give them credit for when displaying MPH.
If I'm not mistaken, there is an allowable % they use to set the speedo. Helps people not get speeding tickets...

Also, in my opinion, warranty should be based on engine hours, not distance. If it were, this issue wouldn't matter, and warranty would be based on a more measurable and objective thing.


Well last time i checked i was the one paying for a ticket, not Nissan. I would rather not have "big brother" looking out for me and give me a accurate reading speedometer.

Not coming at you, just seems like a rediculous reason to have a inaccurate gauge.

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disallow
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Re: MPH Discrepancies

Postby disallow » Mon May 31, 2010 7:09 am

hmatiak wrote:
Well last time i checked i was the one paying for a ticket, not Nissan. I would rather not have "big brother" looking out for me and give me a accurate reading speedometer.

Not coming at you, just seems like a rediculous reason to have a inaccurate gauge.
Not everyone is willing to take responsibility like you are. Most people I know are looking for other things to blame.

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Postby Captain » Mon May 31, 2010 8:39 am

Its been talked about before. I changed my tire size to 265/70r17 to compinsate for this.

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Re: MPH Discrepancies

Postby NVSteve » Mon May 31, 2010 1:38 pm

hmatiak wrote:A on going issue with my last two Nissans. Bought a '07 Xterra brand new and put our GPS on the dash. At highway speeds the speedo was 2-3 mpg off. After having it checked by the dealer and them finding nothing i tested with another gps, same thing, still off. The problem was only solved by going up a tires size, 265/75/16.

Having the same issue with the new Pathfinder. Speedo is off the same amount.
Yeah, we've talked about this same thing a number of times on this forum. The PF is calibrated to the largest stock size allowable, which on 16" wheels is the 265/75/16. Anything smaller will give false MPG & MPH, the former of which is why a number of people here have seemingly much better MPG than the rest. One would think it would be a very easy thing to be able to reprogram the computer to allow for a different size of tire, but no such luck. I've had this conversation with Nissan more than once.
Currently Honda has a lawsuit against them for the same infraction. The speedometer reads faster than you are actually traveling. Racking up miles faster and sooner than if it were not reading 2-3 MPH faster than it should be. Putting you out of warranty coverage sooner than it should.
Honda, as in one of their car models? I agree that the readings should be accurate, but not worthy of a lawsuit. Now, if the readings were less than reality, everything would be completely different.

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hmatiak
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Re: MPH Discrepancies

Postby hmatiak » Mon May 31, 2010 4:00 pm

NVSteve wrote:
hmatiak wrote:A on going issue with my last two Nissans. Bought a '07 Xterra brand new and put our GPS on the dash. At highway speeds the speedo was 2-3 mpg off. After having it checked by the dealer and them finding nothing i tested with another gps, same thing, still off. The problem was only solved by going up a tires size, 265/75/16.

Having the same issue with the new Pathfinder. Speedo is off the same amount.
Yeah, we've talked about this same thing a number of times on this forum. The PF is calibrated to the largest stock size allowable, which on 16" wheels is the 265/75/16. Anything smaller will give false MPG & MPH, the former of which is why a number of people here have seemingly much better MPG than the rest. One would think it would be a very easy thing to be able to reprogram the computer to allow for a different size of tire, but no such luck. I've had this conversation with Nissan more than once.
Currently Honda has a lawsuit against them for the same infraction. The speedometer reads faster than you are actually traveling. Racking up miles faster and sooner than if it were not reading 2-3 MPH faster than it should be. Putting you out of warranty coverage sooner than it should.
Honda, as in one of their car models? I agree that the readings should be accurate, but not worthy of a lawsuit. Now, if the readings were less than reality, everything would be completely different.
Honda Motor Co. IIRC, it was a group of owners who got together, not sure on which model. I did the math once, and a reading of 2-3 MPH faster than what is true can put you out of warranty coverage a good bit too soon. Ill have to do the math again and post the #'s.

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Postby fat_frog » Mon May 31, 2010 4:33 pm

I don't remember when and where, but I do recall reading an article about testing speedmeter on vechiles from multiple manufacturers. ...their speedmeters...domestics & imports all consistently showed slower than the actual speed...measured by the radar gun.

I also do not recall what the responses from all those manufacturers were, though.

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Postby skinny2 » Mon May 31, 2010 5:45 pm

IIRC, the Honda Odo was about 5% off. I believe they extended the 36k warranty to 37k-38k. My PF is off 2.5mph at 70 (72mph on odo = 70mph on GPS) or about 3.5%. Most vehicles are off 2-3% based on prior experience so the PF is on the high side of acceptable in my book. I adjust for this in my head...not interested in the performance/economy hit that comes along with bigger tires.

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Re: MPH Discrepancies

Postby mar1 » Mon May 31, 2010 11:30 pm

hmatiak wrote: Honda Motor Co. IIRC, it was a group of owners who got together, not sure on which model. I did the math once, and a reading of 2-3 MPH faster than what is true can put you out of warranty coverage a good bit too soon. Ill have to do the math again and post the #'s.
dude, what math?

100 mph is actually 98 mph

so 60000 is actually 58800.

worth a lawsuit for an additional 1000 miles? and usually dealerships fix stuff under warranty even after the 60000 mark by a bit.

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Re: MPH Discrepancies

Postby skinny2 » Tue Jun 01, 2010 5:28 am

mar1nasr wrote:
hmatiak wrote: Honda Motor Co. IIRC, it was a group of owners who got together, not sure on which model. I did the math once, and a reading of 2-3 MPH faster than what is true can put you out of warranty coverage a good bit too soon. Ill have to do the math again and post the #'s.
dude, what math?

100 mph is actually 98 mph

so 60000 is actually 58800.

worth a lawsuit for an additional 1000 miles? and usually dealerships fix stuff under warranty even after the 60000 mark by a bit.
Try again. The 2-3mph number is at 65. So if speedo says 68mph and you're actually running 65mph a 4% variance. So at 60k miles when your warranty runs out you've actually only driven 57,600. No that's not a lot but it's worth calling a spade a spade. I'm sure it was just attorneys looking for a settlement but either way there is some loss here to the owners. Someone leasing could be hit with .15/mile for miles they didn't drive and everyone else loses value due to the miles.

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myriad46
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Postby myriad46 » Tue Jun 01, 2010 6:08 am

Anybody have a speed trap gun? We can resolve this real quick.


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