2015 Genesis computer inaccuracies

[magicsquid]

Has anyone else detected that their dash reported MPG is approximately 10% better than reality? I've had my 2015 for only 2 months, but the MPG reported by the car is 2 miles per gallon better than reality (dividing number of miles driven by gallons of fuel used as determined at fill up time.)

On top of that the speedometer is inaccurate as well, which may be contributing to the erroneous MPG readings. I've had it to the dealer for this issue and they say it's within normal readings.

The problem is that the analog speedometer doesn't even match the digital speedometer on the dash, and on top of that, those are both wrong too. For example, if the car is actually going 70 MPH as reported by multiple GPS units, the analog gauge says it is doing 76 MPH and the digital gauge says it is doing 74 MPH.

The dealer also says it's normal for those two gauges on the car to be different AND for both of them to be wrong. This is the first car I've had where the speedometer is more than 1 MPH off. Anyone else have these issues?

 

[wasnt]

I've found GPS based MPH isn't always accurate.

Also, I have noticed in every car I've owned, that the reported MPG are a bit friendlier than they actually are. My Honda was reporting about 4 MPG higher than what was I actually getting.

 

[jarred52]

The analog and digital speed readings of my Avalon were about 2 mph different. The dealer service said that there is no way to calibrate them to read the same. My MB E320 cdi and my Genny both read the same. On my next road trip, I plan to do a manual calculation of mpg but so far, it is estimate accurate.

 

[Alwaysforward]

My analog and digital gages are matching. Drove by a few of those Police post "Your Speed Is" signs and it is dead on to those.

 

[xsolara]

Every car I have ever owned with computer read out has been off by 5-10%.
It is very hard to calculate mpg by miles driven and gas used because of so many variables
( outside temp, pump shutoff, altitude, ETC) The system I use is a yearly computation .... yearly mileage and total gallons purchased.... IE: my 2012 Azera for 2014 MPG was 27.9
As far as I'm concerned the MPG readout is only a rough guess

 

[CanukV6]

So your Analog speedometer is 8.5% high and the digital display is 5.7% high. I don't think that is unusual in my experience. Better high than low .
The analog speedo is usually taking its signal from a sensor on the gearbox or rear axle, so it is based on the gearing not actual road speed. The tire diameter is part of that gearing and the diameter can vary slightly according to tire size, tire wear, temperature and road speed.
The digital readout should be getting its signal from the GPS so it ought to be more accurate.

 

[RN2X]

I have not noticed if my two speedos match but my digital is 1-2 miles off from the gps speed presented in the nav. and the same with gps on my phone. The computer calculates my mpg about 2 mpg higher than manual

 

[amartz]

When I set the cruise to 80, and the speedo reads 80, Waze reports 79. Not too bad, I guess!

 

[JimInNashville]

Detailed records for a 2010 Genesis and two different 2015 Genesis models show ALL THREE give fuel consumption estimates that are "optimistic" by 5-10%. My rental Sonata also had the same characteristic. OF COURSE Hyundai could fix this if they wanted to.

 

[srobak]

All 3 speedos on my G2 are within 1mph of each other. They are also within 1mph of Waze on my phone, a Garmin GPS, a TomTom (don't ask), and a "Your Speed" sign.

Almost all trip computers are inaccurate during the first half of a tank of gas... I've seen almost as much as 10%. That number quickly diminishes when you cross the half-tank threshold.

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[StarPower]

My analog speedometer, digital/HUD, and GPS on my phone are all usually within about 1 MPH of each other and consistent with "your speed is" signs. I believe the digital speedometer on the cluster/HUD comes from the same sensor as the analog speedometer, not from GPS. I routinely drive in areas that have no GPS signal, and the car's digital speedometer remains accurate in these areas. The GPS will often read significantly lower in these areas.

 

[Mark_888]

GPS MPH should always be accurate over any reasonable distance. Any inherent error will be reflected in both the start and stop positions used to calculate it.

Most manufacturers overstate their MPH on the instrument gauges to keep owners out of trouble with the speed limits and to provide an extra margin of safety. This is done so that if there is an inherent error somewhere in the measurement (such as changes in tire diameter as the tread wears, etc), then the driver will still be below the actual MPH and the manufacturer will not get sued by the owner or sued someone involved in an accident.

As far as MPG, this is to make the owner feel good about the purchase and to give everyone the benefit of the doubt. One of the fundamental principles of selling autos is that, it doesn't matter how good a deal a customer gets as to whether they are happy, it only matters how good of a deal the customer thinks they got that matters.

For example, this is why ALL demos (which were punished hard by customers during test drives) are claimed to have been only used by the dealership owner or GM, etc, for personal use, and never driven by customers.

 

[Midnightsun]

GPS MPH should always be accurate over any reasonable distance. Any inherent error will be reflected in both the start and stop positions used to calculate it.

Most manufacturers overstate their MPH on the instrument gauges to keep owners out of trouble with the speed limits and to provide an extra margin of safety. This is done so that if there is an inherent error somewhere in the measurement (such as changes in tire diameter as the tread wears, etc), then the driver will still be below the actual MPH and the manufacturer will not get sued by the owner or sued someone involved in an accident.

As far as MPG, this is to make the owner feel good about the purchase and to give everyone the benefit of the doubt. One of the fundamental principles of selling autos is that, it doesn't matter how good a deal a customer gets as to whether they are happy, it only matters how good of a deal the customer thinks they got that matters.

For example, this is why ALL demos (which were punished hard by customers during test drives) are claimed to have been only used by the dealership owner or GM, etc, for personal use, and never driven by customers.

My take is all manufacturers overstate the mph from actual because the recorded figure ( less than you have actually driven) gets you out of the warranty quicker than if they would do the opposite. Food for thought.

 

[Mark_888]

My take is all manufacturers overstate the mph from actual because the recorded figure ( less than you have actually driven) gets you out of the warranty quicker than if they would do the opposite. Food for thought.

I would not doubt that is a perceived benefit to the auto makers. However, not all cars have their MPH linked to the odometer (especially older ones).

As mentioned before, the actual miles driven and MPH does vary depending on the diameter of the tire, which varies by tread depth, or even wheel size option, so they want to make sure that under no circumstances will the car report a slower MPH than is actually happening. Legal liability issues are usually of the upmost importance when making such decisions.

 

[sub780lime]

Driving a couple hundred miles this weekend, waze and my speedo were all within 1 mph.