How do you guys estimate Fuel Mileage?

[Calboy]

Hey Guys,

 

How do most of you decipher your gas mileage? I am looking at adding a couple of upgrades to see if my gas mileage improves. Are you using the truck feed back on the dash or going old school and calculating from a full tank to empty based on miles? If you are using the truck feedback how accurate do you feel it is?

[shakenfake]

Both. I find that modern day vehicles are pretty damn accurate though with their mileage calc

[TxTruckMan]

The DIC is close enough unless you're going for perfection.  Then you would have to note down gallons per fill up and track mileage through an app or something.

 

And good luck with mileage improvements.  GM already squeezes the turnip pretty hard due to CAFE penalties and such.

[redwngr]

Both.

 

I log every fill and record both trip meter and hand calc for comparison.  

 

Lots of things impact the fuel economy of a given fill.

If you trying to see a change, then you'll need multiple fill before and after to be able to take out the normal variation from your observations.

 

If you change tire diameter it'll kinda screw that up -- since it will change the wheel revolutions per mile.  

[Grumpy Bear]

@redwngr's method is the method I also use. Here's one I started about 15,000 miles ago hand calculated. As you can see the tank to tank number is all over the map so a longer term average is needed to 'see' the data and find cause and effect. 

 

 

Here's one for over 100,000 miles on another truck that shows longer term seasonal changes. I do this to parse the difference between the effect of a change and the effect of the seasons. 

 

 

The information on the DIC is useful as instant feedback if you use it as such to modify habits but not much use in establishing trends and treads are required to parse 'cause and effect'. Even when they are not accurate they are directionally so which is helpful in behavior modification. As far as how accurate; some are, some are not. But you will find out comparing to the hand calculated numbers. 

 

May you find this useful. Enjoy your day. 

Edited December 14, 2021 by Grumpy Bear

[KARNUT]

On a new vehicle to me I hand calculate and compare to the display. After a few times I use the display mindful of any difference. Then it’s up to my right foot.

[Transient]

I don't.  If I was worried about mpg I would've bought the diesel engine. 

[Silverado4x4]

For the life of me I just can't understand why people want to sink hundreds of dollars to try and improve fuel mileage as the money you spend to try and pick up maybe 1-2 mpg will take you years and years to pay for the money spent for the upgrade.

[Transient]

4 minutes ago, Silverado4x4 said:

For the life of me I just can't understand why people want to sink hundreds of dollars to try and improve fuel mileage as the money you spend to try and pick up maybe 1-2 mpg will take you years and years to pay for the money spent for the upgrade.

Kinda like people who pay $10k-$20k more for a hybrid instead of a gasser when it'll take years and years to pay for the money spent for the upgrade.  Fools and money are often departed.

[It's Tim]

3 minutes ago, Silverado4x4 said:

For the life of me I just can't understand why people want to sink hundreds of dollars to try and improve fuel mileage as the money you spend to try and pick up maybe 1-2 mpg will take you years and years to pay for the money spent for the upgrade.

Agreed.

It's silly to "buy" a vehicle when one can't afford the fuel. 

[WeGone]

I just watch the fuel gauge when it hits 1/4 tank time to fill up!

 

[TxTruckMan]

Agreed.  There is no positive outcome to this venture.  Especially since GM already does their best and spends MILLIONS to try and squeeze out a half MPG here or there.  There is no easy aftermarket upgrade for improved mileage.

[Black02Silverado]

I use the Fuelly app.  Keeps track of all our vehicles.  You just put in mileage, gallons and price.  I like it.

[BlancoSilverado]

I ran 2 tanks and hand calculated my gas mileage early on. i'm actually .2/.3MPG better then the DIC. 

I used this to verify how close my DIC is to actual. 

Use the trip to keep it separate. 

[Grumpy Bear]

5 hours ago, Silverado4x4 said:

For the life of me I just can't understand why people want to sink hundreds of dollars to try and improve fuel mileage as the money you spend to try and pick up maybe 1-2 mpg will take you years and years to pay for the money spent for the upgrade.

 

That would be true if the cost to improve mileage were in fact hundreds of dollars. Some do and your point is well taken.

 

But:

 

Consider how much money it cost to modify behavior vs net gain in mileage? Simple feedback methods the cost you nothing but time can and have, in my case, netted gains of 17%. Paying close attention to fuel vs tire pressures, while not a gain, prevents a loss that is an average killer. A change of motor oil I've recorded a repeatable gain of 5%. It cost me nothing but the effort to make a choice and the personal effort to parse out. Trip planning that limits the number of 'cold starts' is HUGE. Few things eat gas like warming up cold lubricants. 

 

There are changes, such as wheel alignment that, given the starting point, can be 5-10%. While one cost, true, the gains are no only mileage but tire wear and safety and no really an 'additional cost' but a benefit from a routine cost done right. There's an alignment where ever wheel is 'in spec' and yet all different and less than optimal and there is a precision lowest drag alignment. They cost the same  

 

It doesn't cost a guy a single red cent to think. Hurts sometimes, but cost nothing.