2014+ Gas Mileage (MPG) Topic

mitchely03 · May 17, 2019

Just did a test for the MPG to and from work on a full tank of gas, 355 miles, filled up just below E and got right at 16MPG.

Trucks lifted 5 inches, 33's, tuned, intake, AFE Ypipe, gibson exhaust. I dont think thats bad at all, I was driving fairly normal as well not too slow or grandpa like.

Tune is 89 however, i think my 91 tune should be worse, like 14mpg.

FlipZ71 · May 18, 2019

3 hours ago, mitchely03 said:

Just did a test for the MPG to and from work on a full tank of gas, 355 miles, filled up just below E and got right at 16MPG.

Trucks lifted 5 inches, 33's, tuned, intake, AFE Ypipe, gibson exhaust. I dont think thats bad at all, I was driving fairly normal as well not too slow or grandpa like.

Tune is 89 however, i think my 91 tune should be worse, like

Nahhh , the 91 tune will net a slightly better result

INTJ · May 18, 2019

The DIC on my truck is a minimum 1-1.2 mpg rosey. It is the least accurate one I have found. Are others that far off hand calculation?

Grumpy Bear · May 18, 2019

1 hour ago, INTJ said:

The DIC on my truck is a minimum 1-1.2 mpg rosey. It is the least accurate one I have found. Are others that far off hand calculation?

My DIC is roughly 7% 'rosey' as you say over a 36 tank sample so about 2 mpg. Worse than yours. The wife's GMC is about 10% happy in spot checks. I don't keep a book on hers.

INTJ · May 18, 2019

I wonder what happened? My 2011 LML was usually within .2.

bmartinez2086 · June 12, 2019

My 2019 Silverado 1500LD just got great gas mileage. Not sure the exact number but I drove from Cudahy, CA to California State university of Los Angeles to pick up a car and towed it on a flatbed all the way to Tucson, AZ and still had 1/8 tank. I filled in Cudahy, CA. I have a 24 gallon tank and drove 62 MPH average the whole way.

mpzz · June 26, 2019

On 6/11/2019 at 9:49 PM, bmartinez2086 said:

My 2019 Silverado 1500LD just got great gas mileage. Not sure the exact number but I drove from Cudahy, CA to California State university of Los Angeles to pick up a car and towed it on a flatbed all the way to Tucson, AZ and still had 1/8 tank. I filled in Cudahy, CA. I have a 24 gallon tank and drove 62 MPH average the whole way.

You either have a 26gal tank or a 34. You went about 500 miles, so if it's a 26, you got about 21.8mpg towing a car on a flatbed. Not likely. So, with a 34 gallon tank you would have gotten about 16.8mpg. More likely, but would be awfully good.

bmartinez2086 · June 26, 2019

1 minute ago, mpzz said:

You either have a 26gal tank or a 34. You went about 500 miles, so if it's a 26, you got about 21.8mpg towing a car on a flatbed. Not likely. So, with a 34 gallon tank you would have gotten about 16.8mpg. More likely, but would be awfully good.

I have a 26 gallon tank I know because I let the light go ine and only 24 gallons went in

mookdoc6 · July 2, 2019

On ‎6‎/‎11‎/‎2019 at 7:49 PM, bmartinez2086 said:

My 2019 Silverado 1500LD just got great gas mileage. Not sure the exact number but I drove from Cudahy, CA to California State university of Los Angeles to pick up a car and towed it on a flatbed all the way to Tucson, AZ and still had 1/8 tank. I filled in Cudahy, CA. I have a 24 gallon tank and drove 62 MPH average the whole way.

Nice...I have 88K and lifetime 19.3? I am fine with that!

scrapen · September 12, 2019

Figured i'd chime on on some of my results before/after and E85 vs 92/93.

2 - 9000 miles - 20.3 mpg per the truck display. (Air raid Jr installed around 5000-5500 w/ Corsa same time, 87 oct with 1 or two tanks of 93)

I never did any hand calculations to verify.

Installed Headers, Blackbear 91 tune (AFM off), l86 manifold, and added E85 capability.

A few weeks ago I went to Tennessee and recorded 5 fill-ups, 3 of which were E85.

7/20 - 9472 - 21.459 - 2.189 (second tank of E85 ran through truck)

8/18 - 9719 - 17.526 - 2.179 E85

8/19 - 10071 - 22.042 - 2.199 E85

8/21 - 10388 - 22.7 - 2.959 (93)

8/24 - 10810 - 22.005 - 2.919 (92 I believe)

The last two fill-ups include driving through Smokey Mountains National Park although the last fill-up was mostly highway.

I did hand calculations for these tanks. I thought I was getting 17.5 mpg after my first all highway E85 and here it was 16 mpg. The last tank my computer said 20.9 (actual 19.2). I see reading a few posts above that it's not just me seeing the computer discrepancies. Safe to say first 9000 miles it was averaging 19.

When I arrived home my computer readout was 23.5. I think it is 23.1 now after a few trips around town. Update 9/20: I noted that odometer was 11111 when I pulled in my driveway on 8/24. Filled up 9/20 @ 11271. Computer said 21.3. Actual 19.8 (23.247 gal)

Until I actually go to a dyno and can compare power numbers i'm not sure if E85 is worth the hassle for me. While $1.00 cheaper than premium where I live, it's also out of the way. Cost per mile is about the same in terms of highway driving. Jury is still out to see how the 91 tune averages out with my in town driving. I may try E30 mixes down the road.

Edited September 21, 2019 by scrapen

3tspapat · November 14, 2019

Anyone done mods that, as a side effect, increased gas mileage? Let's hear it!

Cowpie · November 19, 2019

On 3/12/2019 at 9:26 AM, CombsL83 said:

Only run E85 in mine and I see around 14 city and 17 highway. Knock off 2-3 each during the winter. Stock 20s, Corsa sport and black bear tune with Afm off is all I have done.

I usually have run E85. I started using E30 a while back and it gives about 93 octane and the mpg's are darn close to regular gas numbers. One can do their own E30 easily at the pump even if there is not a specific E30 pump around. Just blend E85 and E10 regular at a 1 to 3 ratio. That will get you pretty close. E85 varies from 51% to 70% depending on the season. E10 is usually no more than E8.

And that probably will not throw a code in a non flex fuel engine. The fuel systems are capable of handing higher levels of ethanol than E10 anyway. Many in the performance auto community do this very same thing with their non flex fuel engines. Getting premium level octane and performance for the price of regular fuel. Great for the 6.2 Ecotec crowd. My wife's Equinox with the 11.2:1 ratio 2.4L in it sure runs good on the stuff and gets only slightly less mpg than the EPA fuel economy number on the original car sticker. Premium fuel for a cost less than regular fuel. What a country! And even with the lower mpg of using E85 or E30, the substantially lower cost compared to premium fuel prices still makes using E85 and E30 cheaper on a cost per mile basis. The mpg numbers may be less, but you will keep more of your own money in your pocket. Of course, prices are regional and may not work to the advantage of everyone.

Edited November 19, 2019 by Cowpie

TXGREEK · November 19, 2019

I’ve heard bad things about using ethanol in your tank during cold winter months, I’m a bit apprehensive about mixing it during the winter months because of the higher water contents in it during cold winter days. Anyone know what temps that pertains to?

Sent from Above

Cowpie · November 20, 2019

On 11/19/2019 at 7:24 AM, TXGREEK said:

I’ve heard bad things about using ethanol in your tank during cold winter months, I’m a bit apprehensive about mixing it during the winter months because of the higher water contents in it during cold winter days. Anyone know what temps that pertains to?

Sent from Above

Have you heard of Heet fuel line deicer that many have used in the winter? Well it is denatured alcohol designed to absorb the moisture in the fuel tank and lines.

I have used E85 exclusively in my 2015 2500 for about 3 years. That is 3 winters and 3 very humid summers. This will be the 4th winter. And my 2500 sits for extended periods. I only put on 4096 miles in the last 12 months. Did the annual oil change a couple of weekends ago. I am now using a E85/E10 blend to make E30 and using it in the pickup and the wife's Equinox.

These fuel systems are closed systems. If the vehicle will be sitting, I keep the fuel tank filled. No real possibility of condensation that way. And even then, what little bit might accumulate the ethanol absorbs and it is cleared out of the system when the vehicle is used. Unless one is actually putting water in their fuel tank, the idea that ethanol will be a problem is not as severe as some try to imply. those tests that show ethanol absorbing water have the E85 sitting in an open container up on a work bench. Of course it will attract moisture in that setting. Or in open vented lawn mowers and other power equipment.

Brake fluid is also hydroscopic like ethanol. Does that mean then that we shouldn't use brake fluid for extended periods? Maybe we should drain and bleed brake systems and fill with fresh brake fluid every couple of months. No, it is a closed system also, just like the EPA mandated fuel systems we have on our vehicles.

Edited November 20, 2019 by Cowpie

TXGREEK · November 20, 2019

Here’s a nice little read I found from a previous discussion on catch cans too, condensation being one of my primary concerns

https://www.gm-trucks.com/forums/topic/212589-the-truth-about-catch-cans/

Sent from Above