2019 LTZ 4x4 5.3L- Concerning MPG

K455 · August 31, 2019

5.3 custom tb6 speed here, getting 18.5 around town 21 highway range tech installed from the very beginning.8700 miles now stock tires.

MacLaren · September 2, 2019

I need to update. I now have a little over 2700 miles I think.

Here's the mileage for the last tank. All rural 2 lane mountain roads with the AC on. Extremely pleased with it!

Sackett10 · September 2, 2019

On 8/14/2019 at 6:29 AM, Moledigger2019 said:

Not here. Getting 17 -18 arount town and just about 22 on highway. Lt trailboss. Loose the lead foot.

I got and get about the same, but with 16- 18 and about 22 on highway. I did improve it by about 1 MPG ave when I installed a tonneau cover.

TrailBoss1 · September 3, 2019

I recently purchased a 2019 Trail Boss LT 5.3. A week after purchase with 100 miles on odometer we drove to our vacation home in DE, 190 miles each way. This was with a mix of rural country roads; some stop and go traffic; and highway (route 1). I consciously drove conservatively, varying speeds and generally staying at 65 mph or under on the highway. I was pleasantly surprised to have averaged 20.6 mpg round trip!!! Very happy with that!

econometrics · September 4, 2019

My "Last 25 mile avg" right now is 12.9. Lol.

I've found that you lose about 1mpg per 5 minutes of idle in the Texas summer heat. I've been doing a lot of 10-15 min remote starts lately, or just sitting in line at Whataburger for 5-10 min. #mpgcrusher

MacLaren · September 4, 2019

3 hours ago, econometrics said:

My "Last 25 mile avg" right now is 12.9. Lol.

I've found that you lose about 1mpg per 5 minutes of idle in the Texas summer heat. I've been doing a lot of 10-15 min remote starts lately, or just sitting in line at Whataburger for 5-10 min. #mpgcrusher

Yes. Sitting idle is an mpg killer.

NeverCold · September 5, 2019

I'm at ~1560 miles and lifetime avg of 17.7 mpg. I've done hand calc for each fill-up and they have been right on with the trip computer.

Worst so far was 15mpg and that was a ton of city, short trips, and stop/go. Last 3 were 19, 18.3, & 18.3 which is a mic of city/hwy. I expect it to avg out to 18. Given my driving, traffic, etc it's exceeding expectations.

Edit to add: lowest overnight temp I've seen since buying it is 79F, so I hope when it cools down I get a little better fuel econ.

Edited September 5, 2019 by NeverCold

Chris Callanan · September 5, 2019

Ya'll make me feel like a lead foot gas hog... I'm only averaging ~11.5 or so... but of course, 95% of my driving is trips of 2 miles in town... (I should just ride my bike)

Still better than my '99 Isuzu Trooper 3.5L - was getting less than 10 in that with a smaller engine and a 1000 less pounds...

Colossus · September 5, 2019

On 8/13/2019 at 8:08 PM, OkStateBass said:

I recently purchased a new 2019 LTZ 4x4- 5.3L. On the truck, I changed the tires at the dealer to Wrangler Duratrac (all terrain) and they also installed a leveling kit.

I have had the truck only a few weeks with now 500 miles on it.

My my concern is that I’m barely getting 12-13mpg in city and 16-17mpg on highway. I’ve been told that the truck needs to be broken in but that doesn’t seem to make sense relating to MPG performance. Is there something I’m missing, maybe the dealer needs to tune or do I just need more time with this truck ?

What state do you live in? I also noticed a decent increase in fuel economy after the first 5000 miles or so on my brand new vehicles. they gradually increased. Also- what type of fuel are you running? (Brand and octane)

Colossus · September 5, 2019

I can get 2-3 MPG better down at flat sea level vs up here at 6000 ft with lots of hills and mountains.

Mrjackson40 · October 5, 2019

Thanks for the info.. just got a 2019 gmc 5.3 ltz x31. I have a about 500 miles on it now hoping to get better mpg than my previous titan. Added flowmaster 10. Not to impressed

MacLaren · October 9, 2019

On 10/5/2019 at 2:11 AM, Mrjackson40 said:

Thanks for the info.. just got a 2019 gmc 5.3 ltz x31. I have a about 500 miles on it now hoping to get better mpg than my previous titan. Added flowmaster 10. Not to impressed

Give her time.

My last full tank of nearly 500 miles, and running Mobil 1 87, I got 23.3 mpg

Very rarely now, do I even drop in the 21 mpg range. This, is just incredible guys. My old 07 Classic got good mpg at 17 & 19

But, hell-oh, looks like I'm gonna get 23 & at least 25 with this 2019.

Edited October 9, 2019 by MacLaren
SpEling

Grumpy Bear · October 9, 2019

On 8/13/2019 at 9:45 PM, OkStateBass said:

Thanks for the replies- what’s the break in period time line? Did you guys experience similar results

I see no one tackled this. My 2015 4.3 just turned over 100,000 miles recently. Over that time it has improved by an average 3% for every 10,000 miles driven. That's the short answer. Could be long time. Maybe over in 50 miles.

(Green bars are winter)

Break-in a funny word we use to describe a very specific duration of accelerated wear any mechanical device sees over it's useful lifespan. Even with modern machining methods wear happens rapidly over a specific duration whose length in miles or time has many factors. Then the device enters a 'steady rate' (not state) condition until nearly used up and finally a second period of accelerated wear and end of useful life.

Joe Average sees wear as something 'baked into the cake' when the OEM designs and builds the device and in part only is that true. They have control over fit and finish, material selection specifics such as hardness and composition.

However, Joe Average has more influence over the device life than the actual design does. For a few quick examples.

1.) The largest impact on wear is: "load" which you have 100% control over past the parasitic loads of the design which are minimal.

2.)The second is: "lubrication maintenance".

3.) The third largest contributor is "state of tune".

There are others but these three shape the curve to the greatest degree.

How this influences MPG: In a word, Friction. Not only a reduction in it but the effects that reduction has on the modern operating systems built into your device such as "AFM" or "DFM" time on both of which are load based and directly tied to the fuel rate. TCM learning maps and so on.

What usually happens: Guys concentrate on the second and third points, ignore the first then blame the manufacture. :idiot:

Just say' n.

:seeya:

Mrjackson40 · October 9, 2019

2 hours ago, MacLaren said:

Give her time.

My last full tank of nearly 500 miles, and running Mobil 1 87, I got 23.3 mpg

Very rarely now, do I even drop in the 21 mpg range. This, is just incredible guys. My old 07 Classic got good mpg at 17 & 19

But, hell-oh, looks like I'm gonna get 23 & at least 25 with this 2019.

Ty!

Texas_Trail_Boss · October 25, 2019

2019 Custom TrailBoss 4X4 CrewCab, completely stock.

I did a down and back from DFW to Texarkana last weekend and found the sweet spot, or what I consider the sweet spot for mileage on this particular truck. On the way to Texarkana, I averaged 19.6 MPG with the cruise set to 2 over the posted limit. An early Sunday departure negated the DFW traffic issues.

On the way back, that fell to 18.2 MPG facing a headwind and 5 over the posted limit. My truck hates high speed and wind really plays a part in wrecking the mileage. I drive it on the HWY 121 tollway in the 80MPH range often and barely get 17.

My commute through the middle of DFW is 22 miles one-way and today the truck showed 20.1MPG on the Lie-O-Meter in the dash.

I wish I could see when this engine goes down to 4 cyclinders like in my Suburban. This motor is the old-version 5.3L with the 6-speed.