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Hypermiling - I'm Getting 28.8 MPG

Wiggums
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z1boss
z1boss

I usually drive with a heavy foot and mostly city so I'm average about 13.5 mph in my Trailboss right now.  I could definitely get better mpgs if I drive easier but I like the power of the engine and

Minnvmax
Minnvmax

To all hypermilers-get the hell out of my way. You are a hindrance on the road.  ??

ShamrockShooter
ShamrockShooter

As best I can tell on the 5.3 8 speed with 3.23 gears right around 51 mph is were it shifts into "8th" gear, and will hold it to about 48 mph before shifting.   So the best possible mpg is going to be

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Wiggums Senior Enthusiast

Wiggums

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I have to point out EPA also uses 100% gasoline, without ethanol. 10% ethanol takes away about 10% based on my experience. I can buy ethanol-free gas in Mexico which is right across the border from here.

Stex Senior Enthusiast

Stex

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I forgot to add to my the DLC not  that accurate for MPG post, that I always buy a truck and worry about MPG.  Driving a brick down the road has to mean one is not or should not be concerned about MPG.  Per my Dad, (RIP), How much rain did you get and MPG answers always require some skepticism. Computer or manual.... :)  

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Wiggums Senior Enthusiast

Wiggums

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19 minutes ago, Stex said:

I forgot to add to my the DLC not  that accurate for MPG post, that I always buy a truck and worry about MPG.  Driving a brick down the road has to mean one is not or should not be concerned about MPG.  Per my Dad, (RIP), How much rain did you get and MPG answers always require some skepticism. Computer or manual.... :)  

 

That's your decision. For me, I get an extra $30 on a trip to Vegas from here doing it that way. In addition to that, I have 99% brake life and I have 1,200 miles on my car right now, thanks to hypermiling techniques. It goes a lot longer than just gasoline.

Others pointed out the DIC is a lot more accurate on the 2019's and after. You brought up the Camaro - completely irrelevant, it wasn't about Camaro, it was about SIlverado. I bet the Camaro owners were talking about the older version of the DIC which wasn't accurate. I have changed my driving habits. A couple months ago, gas was $4.29 a gallon. Some areas were $4.39 or even $4.49.

 

Not everybody lives in Texas, ya know?

Edited by Wiggums
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Grumpy Bear Senior Enthusiast

Grumpy Bear

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My 2015 DIC seems to top out at 33.3 mpg for the tank. I've actually hit that once hand calculated but it shows that number anytime I'm over 30 mpg. 

Edited by Grumpy Bear
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383 Enthusiast

383

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11 hours ago, Stex said:

I forgot to add to my the DLC not  that accurate for MPG post....Computer or manual.... :)  

I never trusted it either unless it was calculated at fill up, but I've been impressed with this one. While I'm filling up, I will divide the miles driven by the average MPG shown to see how many gallons it should take to fill up. It's almost always within .1-.2 gallons, varies mostly if the fuel area isn't level.

Black02Silverado Senior Enthusiast

Black02Silverado

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I use Fuelly app.  I really like it and if I hand calculate it is spot on to Fuelly.  Especially on my Cruze diesel, which I fill up to the very top of the filling neck every time I fill up.

swathdiver Senior Enthusiast

swathdiver

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15 hours ago, Philipgonzales3 said:

They get up to 80 on the high speed test and 60 on the highway test...

 

13 hours ago, Grumpy Bear said:

You reading the same charts I am?

Sorry fellas!  You're right, I shoulda kept on reading!  LOL

 

I have run my own mileage tests for my truck in 5 mph increments using multiple 2-way averages on the flattest roads around and run them at night when the wind is calm.

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Wiggums Senior Enthusiast

Wiggums

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7 minutes ago, swathdiver said:

 

Sorry fellas!  You're right, I shoulda kept on reading!  LOL

 

I have run my own mileage tests for my truck in 5 mph increments using multiple 2-way averages on the flattest roads around and run them at night when the wind is calm.

 

The German TÜV does that at 60 km/h, 90 km/h, and 120 km/h, I wish somebody would do that here!!! I don't smash my gas, I don't floor it while going uphill.

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swathdiver Senior Enthusiast

swathdiver

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The DIC calculation system is pretty accurate in my truck (GMT900) if I recognize a few things.  First, it does not account for remote start fuel usage or time (I think).  And, it should be reset with each tank to ensure the best tank to tank accuracy or else it will give the long view and not move so much, might say 14.6 when one tank was 16 and another 13 and barely moved a tenth.

 

The DIC allows us to compute from the Odometer, Trip Odometer, Hour Meter, Trip Time, Fuel Used and we can use that with Fuel Pumped to run multiple calculations and average them all out.

 

So I can then compute Distance 2 ways, Time 2 ways, Fuel Used 2 ways, Speed, GPH and MPG 2 ways as well.  Then I have formulas for Miles per Dollar and Cents per Mile.

 

Since the truck runs on three different types of fuel, averages are made for all three, Price per Gallon, Center per Mile, MPG, GPH and MPH.  I'll also further break it down to alcohol content percentages.  Average of averages of averages.  I have no idea what are the accepted standards, just what seemed right to me at the time I made those excel based calculators.

 

 

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HondaHawkGT Senior Enthusiast

HondaHawkGT

Posted
Posted
On 6/4/2019 at 3:47 PM, aseibel said:

I just drove over 1000 miles down to Iowa and back and I was very close to 20 mpg on each of 3 tanks. (Both DIC and hand checked) I was cruising around 72 mph for most of it. 3.42 gears.

 

My truck has an EPA rating of 22 highway. I believe the EPA test to determine highway mpg is done at below 60 mph. So it makes sense that they would get 2 mpg more at a slower speed.

 

Anyway, it is known that the truck is not exact with its calculations. I wonder how much coasting throws it off. If you spend more time coasting that the average driver, the DIC often reads 99 mpg during that part, but that isn't technically accurate. No one seems to know the algorithm that the computer uses, whether its a sum of all the instantaneous readings, or what. But doing the math yourself is more exact for your driving- miles driven/ gallons burned. But that also includes any amount of fuel you waste cold starting, idling, remote starting, or otherwise sitting in traffic. So even though your engine is running, if you are not moving, that fuel doesn't contribute to your moving fuel efficiency. The calculation is more representative for your cost of ownership per mile than actual fuel efficiency of the vehicle. The longer your average trip, the more accurate the number should be due to less idling and cold starts.

The computer shouldn't have any problem tracking fuel use as long as the MAF sensor and fuel sustem sensors are accurate. And during deceleration when DFCO is active and the instant fuel economy reaches 99, there's no fuel being burned at all. The engine is spinning via the TCC. 

 

The Fast Lane Truck has done a lot of real world highway fuel economy tests and for the most part, the GM computer has been surprisingly accurate. Any computer estimate that's routinely within 1 MPG of the hand calculated number is good enough for me.

 

 

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