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Discussion Starter · #1 ·
Has anyone figured out how to recalibrate the speedometer / odometer? I assume there's a way, since the differing tire packages all have different rolling circumferences, thus altering the speed / distance calculations.

My SQ4 with 20" Urano / P-Zeros registers about 4% optimistic (faster speed / longer distance) than actual. Have verified this on 10 mile runs on the interstate, as well as with my Passport Max GPS-based speed calculation.

I plan to have this addressed by the dealer on my first service, but I would like to be able to tweak it myself. Is there a service menu with a trick entry that we can get into (a la BMW, Lexus)? Or does it require access via the OBD thingy? Or is it just not possible?
 

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So are you indicating the odometer is probably clicking up mileage faster than it should? Funny you should say that because I have the 20" Urano's/PZero and I could swear I put on more miles on the same trip with the Ghibli than my Escalade .. but never did the due diligence to prove it.
 

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Discussion Starter · #3 ·
So are you indicating the odometer is probably clicking up mileage faster than it should? Funny you should say that because I have the 20" Urano's/PZero and I could swear I put on more miles on the same trip with the Ghibli than my Escalade .. but never did the due diligence to prove it.
Yes, that's what I'm seeing. Hmmm ... perhaps it's all a company plot to shorten the warranty coverage by 2,000 miles.
 

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Every car I've owned, regardless of brand, has had the speedometer read about 10% optimistic, but the odometers have always been dead on. This implies that the manufactures are purposely skewing the speedo.

Are you saying your odometer readings match your speedometer, but both are different than GPS or the highway mile markers?
 

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Discussion Starter · #5 ·
Every car I've owned, regardless of brand, has had the speedometer read about 10% optimistic, but the odometers have always been dead on. This implies that the manufactures are purposely skewing the speedo.

Are you saying your odometer readings match your speedometer, but both are different than GPS or the highway mile markers?
Yes, exactly. Both the speedo and odo are optimistic (i.e. the instruments claim we're travelling faster and further than we actually are). The error is on the order of 4% -- actually 4.3% for the odo which is a giant pain for rallys, and a little under 4% for the speedo (about 2 mph at 60).

My experience with other cars has varied considerably. In the fifties 10% optimism on the speedo seemed to be the norm; in later years they seemed more accurate (or maybe I could afford better cars!).
 

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I have a 21' equipped car and my odometer is off about 18% on the trip counter and over 20% on the full mileage counter. I am addressing this with Maserati but I would appreciate if there are owners of cars with the 21 inch rims and 20 inch rims that have addressed that (I had a 19 inch-equipped loaner and mileage is accurate).Thanks!!
 

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the only method i know of would be to insure that the bcm vehicle configuration is set up correctly for the wheel/tire size of the vehicle. factory scan tool work that is, along with the technician communicating with maserati tech support.
 

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The only time it's going to be close to accurate is running brand new tires.

Once the tires are worn down the become smaller and as a result they are spinning quicker and more revolutions per mile. My BMW is off 4%, confirmed via radar and GPS speedo. It's BS.

You can put on a larger tire to make up the difference.

It's a giant problem for those that lease a car or at resale time.
 

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My Ghibli S Q4 with 18" wheels reads 2MPH over actual speed as confirmed by Smartphone GPS and my $650 Escort detector. So I know the car is wrong.
81 on speedometer means I am going 79.

Master Tech. at dealer says nothing can be done about that...
 

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Speedo's can be off as much as 10% as long as they read faster than the actual speed. They are only accurate between aprox. 40-60 mph. Any more than 10% then a trip to dealer would be needed. Just make sure you have original tire and wheel sizes on the car.
 

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seemingly everytime they are off its always in the dealers favor though and they read high. put slightly bigger tires / wheels on and let it record low. leased cars never really get the full mileage that they pay for when these things read high. my bmw is 5% high, its always a percentage, never just a flat number, so when travelling 60 its off by 3mph, when travelling 100mph its off by 5mph.
 
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