Instant MPG

[Bob_Vaughn]

I recently purchased a 2013 GMC 3500 diesel truck and on the dic it will give me average MPG and the owners manual states that instant mpg is available if so equipped. My question is is it a software or hardware issue and is it something I could have the GMC dealer add? I wish the mfg. would make a manual that matched the vehicle that you purchase with just what is on the vehicle in the manual....

[edatlanta]

I use this and use the Torque app to see instant mpg on my smartphone or tablet. My ecm has this information but my dic doesn't support it. Works great and there are other things you can load to watch also such as boost,fuel flow,coolant temp and more

[PapPappy]

You do realize that "Instant MPG" doesn't mean that you're gonna instantly get more MPGs, right:?:B

Would be nice to be able to push a button, and go from 7 MPG to 10 MPG......or tap it several times, and get up to 20+ MPG:B

[N-Trouble]

The older Duramax's did have instant MPG but it was removed in 2007 I believe when they went to the new body style.

[travelnutz]

Our 2004.5 Chevy D/A also has both instant and average MPG's given on the DIC (Driver Information Center). In the nearly 150K miles the truck has gone since we purchased it new, I've never yet seen even .2 MPG difference between the DIC readout and hand calculated MPG's. I'd call that being very accurate! I always fill it to 1" to 2" below the filler tube top for accurate repeatability in fueling.

Can't be real accurate when I have the 100 gal aux tank in the bed when towing the 5th wheel as being parked on slight angled surface under the truck makes several gallons difference added before the level reaches the same point of reference at the filler opening. Can be very close over 3 or more fillups but that takes a lot of miles of travel to use that much fuel. Can't have the TC and the aux tank in the bed at the same time so MPGs can be found with accuracy.

[2-MTnesters]

My 2004.5 GMC is equipped with average and instant MPG. Not sure about the newer ones.

[azwildcat99]

With GM, I think the instant is only available on vehicles with the Active Fuel Management engines.

[N-Trouble]

Regardless of what the manual says only average MPG is available. No option to add instant. You do get somewhat of an instant MPG for a few seconds after each reset.

On Some trucks the avg MPG is accurate but most of the time they read high because the computer assumes less fuel has been consumed than actual. I am always able to add more fuel to my truck 1-1.5gal than the computer says has been used since last fillup. You need to compare hand calculated values to the computer readout for a few tanks to get an idea of how accurate yours is.