Accuracy of "Average Fuel Consumption"

[wild willy]

I also have a GTO and remember you from that forum. You were never too happy with the GTO, if I remember correctly.

100% incorrect. I absolutely loved the car and it was the best built car I ever owned. What pissed me off was the rattle in the exhaust that was fixed once and came back and GM said that it was normal because they did not want to replace the 1400.00 exhaust system again.

Great car..I wish I would have bought it in place of the lease. 123.00 month for 23 months with Zero down........Who knew I'd fall in love with a GM

 

[Flyboy]

One more data point -
2009 4.6 right from the dealer in PHX two day drive to SEA (Seattle) 28.6 mpg. Running to and from work now - 50-50 in-town and highway doing 22.5 at 3000 mile mark. Speedo right on at 65 mph to a ton, running one mph low at 35. But with that tech package, stereo, ride and power...it's just hard to get out of the saddle...man what a fun ride!

 

[Duaine]

I have the 4.6 w/tech pkg. I have checked my actual mpg against the cars computer and it has been right on so I have kind of quit checking it. Oh by the way I usually average 23 mpg with it. I have only took one longer trip of 200 interstate miles and ended up at 27 mpg. Temerature at the time was 50 F in very calm conditions. I was running between 70-75 mph since I wasn't in a big hurry and enjoying the great Lexicon stereo. I hope this helps some potential buyers.

Let me also just briefly say that I read one post of a guy almost paranoid to buy based on a few electronic issues. I have had my Genesis since Nov. of 08 and use all the electronic toys and not one problem.

And also yes I would like a softer smoother ride and I have already made that known and I am not one who posts my dislikes over and over again.

 

[Grit]

My actual fuel mileage is 2 mpg less than the autos calculations!! However I'm happier using regular octane fuel than the premium my BMW 545 required! Mileage is about the same as the former Beemer and I have alot more room!

 

[CanukV6]

The original post said the average mileage calculator resets after every fill-up. Mine doesn't. It just keeps rolling along. I have reset mine manually by bringing it up on the display and pressing the 'Reset' button, but it has never done this automatically.

Over mixed driving on a tankfull I average about 26mpg and I have verified that by logging actual mileage and fuel used - fill-up to fill-up. I am delighted with that number as I am a dedicated leadfoot and don't drive for maximum economy.

 

[Mark_888]

The original post said the average mileage calculator resets after every fill-up. Mine doesn't. It just keeps rolling along. I have reset mine manually by bringing it up on the display and pressing the 'Reset' button, but it has never done this automatically.

I assume you have a Canadain model, and there are differences. There are even two completely different displays documneted in the owners manual.

 

[Bear]

I seem to be the only one not getting great gas mileage. A recent trip from the eastern Iowa area to Boulder, CO and back, using gas receipts and the odometer reading I had an average of 22 mpg. I have the V8 and was driving the speed limit. In city driving is 16 mpg.

 

[Mark_888]

I seem to be the only one not getting great gas mileage. A recent trip from the eastern Iowa area to Boulder, CO and back, using gas receipts and the odometer reading I had an average of 22 mpg. I have the V8 and was driving the speed limit. In city driving is 16 mpg.

How many miles on the car? What kind of break-in routine did you use? Have you had any oil changes (what type and grade of oil was used).

It is possible that you got a lot of ethanol gas that affected your results.

Do you use regular or premium? Also, if you bought gas in CO and drove to Iowa, you got screwed because the gas in CO has lower octane to adjust for the higher altitude, and by the time you hit Kansas the octane may have been below minimum specs for the car. Anytime you buy gas in CO and and head home to lower ground, make sure you fill up with premium and do frequent fill-ups on route to dilute the CO gas.

 

[GenesisCaptain]

Gotta resurrect this thread from deep sleep. The car's calculated Average Fuel Consumption on mine is awful. Mine is 2 to 3 MPG higher than reality. I typically see 23.5 or slightly higher on the screen, but the fill-up gallons divided by miles driven is typically around 20.5.

It is what it is, but this is a constant annoyance to me. I'm not complaining about my fuel efficiency-- it is way better than before-- but the presentation of the data. My previous two cars were within 0.5 MPG (<5% error), which I can live with. 10% to 15% inaccuracy is borderline useless.

 

[Southern Boy]

I just did a fill up and the average MPG on the display was 22.1 and when I ran the numbers the actual was 21.7 MPG.
I replaced my OEM 17” wheels and tires (225-55-17) with 18” wheels and 225-50-18 tires in June of this year which causes the speedometer to read 0.04% slower than actual speed.
At 60 MPH indicated the actual speed is 60.3 MPH so the Display is pretty close to actual MPG. I would say the breakdown for highway vs. city driving is approximately 40 / 60%

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[xiaphin]

The MPG on the computer is not accurate. Mine has been consistently high by 1.5 MPG when compared to manual calculation. Mileage/Gallons. 27.2 on computer and 25.7 manually on last tank. 75% highway and 25% city.

 

[Mark_888]

I replaced my OEM 17” wheels and tires (225-55-17) with 18” wheels and 225-50-18 tires in June of this year which causes the speedometer to read 0.04% slower than actual speed.

The difference in diameter between these two tire sizes is probably less than the difference between a new tire vs one that close to needing to be replaced due to tread wear.

 

[SmoovC]

Bought 2012 5.0 non R-Spec new, here are my results of showing vs. actual MPG:

1st tank: shows 18.5, actual 17.78, difference -0.72

2nd tank: shows 18.4, actual 16.68, difference -1.72

3rd tank: shows 20, actual 17.66, difference -2.34

4th tank: shows 19.1, actual 17.83, difference -1.27

5th tank: shows 19.4, actual 17.82, difference -1.58

6th tank: shows 18.8, actual 17.81, difference -0.99

7th tank: shows 19.3, actual 18.54, difference -0.76

8th tank: shows 17.6, actual 17.82, difference +0.22

9th tank: shows 18.9, actual 17.70, difference -1.2

10th tank: shows 19.3, actual 17.92, difference -1.38

11th tank: shows 18.6, actual 17.51, difference -1.09

Average shown: (207.9/11) = 18.90

Average actual: (195.07/11) = 17.73

Average difference: 1.17 mpg higher showing than actual.

Driving conditions are mostly mixed; more city and back roads than freeway driving. Fuel is always premium Union 76. Tire pressure is 35 fronts, 33 rear. I found this combination to reduce understeer.

 

[Mark_888]

The MPG on the computer is not accurate. Mine has been consistently high by 1.5 MPG when compared to manual calculation. Mileage/Gallons. 27.2 on computer and 25.7 manually on last tank. 75% highway and 25% city.

This falls under the well-known principle in automobile marketing/sales that what matters most in terms of customer satisfaction is not whether a customer got a good deal, but whether they think they got a good deal.

It seems that Hyundai has fudged the MPG numbers just a bit in this regard (and also in their EPA tests) in an attempt to make us feel better about our purchase. Instead, some may feel they have been slimed (but most customers do not read this forum).

 

[Crusty Old Shellback]

It seems that Hyundai has fudged the MPG numbers just a bit in this regard (and also in their EPA tests) in an attempt to make us feel better about our purchase. Instead, some may feel they have been slimed (but most customers do not read this forum).

Care to show us your documented proof that they fudged the numbers?

From what I've read on the matter, they had used an old formula and didn't know the EPA had changed it. Once they found out the formula had been changed, they fixed the issue.

"The companies said the mistakes stemmed from procedural differences between their mileage tests and those performed by the EPA."

"Sung Hwan Cho, president of Hyundai's U.S. technical center in Michigan, said the EPA requires a complex series of tests that are very sensitive and can have variations that are open to interpretation. The companies did the tests as they were making a large number of changes in their cars designed to improve mileage. The changes, such as direct fuel injection into the cylinders around the pistons, further complicated the tests, Cho said."

"This is just a procedural error," he said. "It is not intended whatsoever."



as found here. http://www.foxnews.com/leisure/2012...i-kia-overstated-gas-mileage/?intcmp=features


As for the accuracy of the shown vs actual MPG, I gave up checking mine as the few times I did, it was correct. I don't focus on the MPG as I didn't buy the car based on the MPG numbers. I just enjoy the drive and the power.

 

[Mark_888]

Care to show us your documented proof that they fudged the numbers?

From what I've read on the matter, they had used an old formula and didn't know the EPA had changed it. Once they found out the formula had been changed, they fixed the issue.

That is not accurate. Hyundai/Kia changed their test procedures in 2010, which is why only 2011-2013 models were affected.

How the Hyundai-Kia mileage rating mistakes happened

An example: Hyundai-Kia used a test track instead of simulated public roads to break in its tires before testing, Cho said. That reflected inaccurate road resistance, the Detroit News reports. Hyundai-Kia changed its test procedures to reflect these calibrations in 2010, but the EPA's Ann Arbor, Mich., National Vehicle and Fuel Emission Laboratory observed discrepancies early this year. That led the agency to investigate. Not long after, a consumer watchdog group pressed claims that the automaker's Elantra sedan didn't get anywhere near its 40 mpg EPA highway rating.
(excerpt from this article: http://www.usatoday.com/story/money/cars/2012/11/02/hyundai-kia-epa-mileage-rating-mistakes/1678163/)​

 

[Crusty Old Shellback]

I guess you skiped over this part of your article.

"Then there's a litany of variations within each test vehicle &#8212; how many miles are on it, the condition of the drivetrain, the tire wear. Finally, the test procedures themselves involve "which kind of regulation and guidance procedures you follow, and how you process the data, and how you calibrate your measurements," he said"

I guess you must have stopped reading after your quoted paragraph, otherwise you would have read this.

""Nobody is trying to con anyone," Andrew Smart, director of industry relations at the Society of Automotive Engineers, told Cars.com. "What you're trying to do as engineers is [create] repeatability &#8230; If there are any subtle differences in vehicle configuration, it's those that are measured and not the driving conditions of the track.""

Or this.

"The EPA could impose civil penalties on Hyundai-Kia, the Detroit News said; Hyundai Motor America President John Krafcik told the newspaper the automaker will fully cooperate. But SAE's Smart maintains the automaker wasn't willfully negligent."

And from this article about sales being up.

" The models that were forced to cut their mpg numbers used newer powertrains rated under an update formula that proved faulty."

http://www.usatoday.com/story/money...r-2012-sales-santa-fe-elantra-sonata/1741749/

 

[Mark_888]

I guess you skiped over this part of your article.

"Then there's a litany of variations within each test vehicle — how many miles are on it, the condition of the drivetrain, the tire wear. Finally, the test procedures themselves involve "which kind of regulation and guidance procedures you follow, and how you process the data, and how you calibrate your measurements," he said"

I guess you must have stopped reading after your quoted paragraph, otherwise you would have read this.

""Nobody is trying to con anyone," Andrew Smart, director of industry relations at the Society of Automotive Engineers, told Cars.com. "What you're trying to do as engineers is [create] repeatability … If there are any subtle differences in vehicle configuration, it's those that are measured and not the driving conditions of the track.""

Or this.

"The EPA could impose civil penalties on Hyundai-Kia, the Detroit News said; Hyundai Motor America President John Krafcik told the newspaper the automaker will fully cooperate. But SAE's Smart maintains the automaker wasn't willfully negligent."

I didn't say that Hyundai/Kia knowingly tried to cheat. But they did change their test procedures (contrary to what you claimed) to achieve more favorable results, apparently because they thought the regulations were open to interpretation without violating the rules. But they were obviously wrong and had to restate the EPA mileage numbers and are providing compensation to consumers.

 

[chicagorspec]

Just filled up the R-Spec tonight. Display showed 21.2, actual 19.7. Mostly city driving with maybe 25% freeway / steady speed.

 

[snork]

I haven't compared all my fill-ups, but I find the trip computer to be 0.5-1mpg optimistic. I do about 65% highway/35% city. Overall I'm averaging 22.5mpg in reality.

The couple longer trips I've taken, I've found the computer to be more accurate at calculating all highway mileage.