2020 AT4 6.2L 10spd fuel economy

AdamAT4 · March 27, 2020

Can someone tell me if it gets better? I knew GM isn't great on fuel in gas engines, duramax is probably best in HD.

I've heard the 6.2 with 10 speed was decent so I test drove and liked it. I didn't want a 3.23 rear end but the 10 speed has a lower first so I figured GM engineers knew what they were doing.

Turns out this thing is a pig, worse half ton I've ever used. I have a 17 power wagon.. big ole 3/4 ton gas 6.4L and 6 speed junk transmission and they are very similar in fuel economy. This AT4 is so bad I get better economy with my F150 EcoBoost with 6" left and 35" 10 ply mud tires.

If it does get better I'll keep it if not I'll go back to the dealer and beg for my old truck back.

Dead flat highway avg is 16-17L/100 or 13 -14 mpg I could get that in my ram towing a trailer.

Please tell me life gets better, I really do love my AT4

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CamGTP · March 27, 2020

How fast you are going?

Jav_eee · March 27, 2020

How many miles do you have on it?

And I seriously doubt you get better mileage on the eco boost. I had one with a 4” lift and 35” load D Toyo AT2s. I know exactly what those get and it ain’t pretty. [emoji23]

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OnTheReel · March 27, 2020

Should certainly be doing better than that. My 6.2/10 speed with 3.42s will get 18-19, flat ground at 80 mph. Granted I don’t have the lift of the AT4 and I have heard the Chevy is more aerodynamic.

Save for the 6.0 in the HDs, the GM V8 trucks have always done very well in fuel economy. Much better than the Ram & Toyota, and on par or better than the EB in many tests I’ve seen.

AdamAT4 · March 27, 2020

How fast you are going?

110 kph, just shy of 70 mph

How many miles do you have on it?

And I seriously doubt you get better mileage on the eco boost. I had one with a 4” lift and 35” load D Toyo AT2s. I know exactly what those get and it ain’t pretty. [emoji23]

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On the same highway I got 14 L/100 with lifted Ford. Before lift I got 10, which is around 22mpg. You also need to realize ford has more options in drive train. I had the, max tow pkg and 3.55s on my EcoBoost, many have 3.42 or 3.31. In lower trim you can get 3.73 and they would be great with 35s on the EcoBoost.

Truck is just shy of 1000km so about 650 miles. I got it with nearly 0

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Jav_eee · March 27, 2020

On the same highway I got 14 L/100 with lifted Ford. Before lift I got 10, which is around 22mpg. You also need to realize ford has more options in drive train. I had the, max tow pkg and 3.55s on my EcoBoost, many have 3.42 or 3.31. In lower trim you can get 3.73 and they would be great with 35s on the EcoBoost.

Truck is just shy of 1000km so about 650 miles. I got it with nearly 0

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Wow you must’ve had a factory freak. Best I got before the lift with the same 3.55 gear ratio was about 18 mpg. After that it tanked to 13. This was at a max of 65 mph. Towing at 70 mph got me 8 mpg.

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smrr1 · March 27, 2020

Speed is a huge factor. Wind is too. Also if you are still using winter fuel that hits it. Do you remote start a lot? All factors. My 19 AT4 6.2/10/323 avg’s 16-17 almost every tank. If i do a road trip i can see 19/20 out if a tank if i watch my speed. If i drive around town and have any fun i get 13. I am very certain the non lifted versions will get better mpg. Maybe by 1-2. A lifted 6.2 is not going to get great mpg. All of my previous 6.2 trucks have done better but i am happy overall with mine.

AdamAT4 · March 27, 2020

Speed is a huge factor. Wind is too. Also if you are still using winter fuel that hits it. Do you remote start a lot? All factors. My 19 AT4 6.2/10/323 avg’s 16-17 almost every tank. If i do a road trip i can see 19/20 out if a tank if i watch my speed. If i drive around town and have any fun i get 13. I am very certain the non lifted versions will get better mpg. Maybe by 1-2. A lifted 6.2 is not going to get great mpg. All of my previous 6.2 trucks have done better but i am happy overall with mine.

I was using highway alone, I have the computer set to the lowest range so it calculated highway only. I was also watching the instant economy to see where it was hovering.

In town isn't great but no heavy vehicle with a gas will be. My jeep SRT is horrible in town but it's a lotta fun tho with the 6.4 hemi.

If I can get 18 mpg on the highway I'd be happy I wasn't expecting it to be as good as my deleted diesel which was 10 to 20 mpg and with 33" stock tires I hit 22mpg. Same truck on 35s was 15-16 towing a SxS and dirt bike or 14 towing my 20' enclosed aluminum v nose.

If this truck keeps getting 14 to 15 mpg I'd be better off losing a few grand to trade in for something different, I dont want another diesel as it takes forever to warm up in our cold winters. (Way up Northern Canada and its -30 to 40) I did get 10k off and 0٪ interest.

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Osteoman · March 28, 2020

My 19 AT4, 6.2 with the factory lift and factory tires gets 16-18 in mixed driving and 18-21 on the highway. I was surprised how good it is. My 17 Ford 5 L never got higher then 16-17.

I do wish I had my 34. Gal tank from the Ford in this Truck though.

AdamAT4 · March 28, 2020

My 19 AT4, 6.2 with the factory lift and factory tires gets 16-18 in mixed driving and 18-21 on the highway. I was surprised how good it is. My 17 Ford 5 L never got higher then 16-17.

I do wish I had my 34. Gal tank from the Ford in this Truck though.

Thanks, maybe it needs to get broke in more.

Do you have a cover? I found my last gas truck made a small improvement on long trips with a tonneau.

I was expecting this truck to have a large fuel tank, I was pretty disappointed when I filled up.

The HD trucks have a 36 or 37 gallon I think.. it's over 130L anyway. Drive a solid 12 hours straight with that.

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truck_newbie · March 28, 2020

15 hours ago, AdamAT4 said:

I was using highway alone, I have the computer set to the lowest range so it calculated highway only. I was also watching the instant economy to see where it was hovering.

In town isn't great but no heavy vehicle with a gas will be. My jeep SRT is horrible in town but it's a lotta fun tho with the 6.4 hemi.

If I can get 18 mpg on the highway I'd be happy I wasn't expecting it to be as good as my deleted diesel which was 10 to 20 mpg and with 33" stock tires I hit 22mpg. Same truck on 35s was 15-16 towing a SxS and dirt bike or 14 towing my 20' enclosed aluminum v nose.

If this truck keeps getting 14 to 15 mpg I'd be better off losing a few grand to trade in for something different, I dont want another diesel as it takes forever to warm up in our cold winters. (Way up Northern Canada and its -30 to 40) I did get 10k off and 0٪ interest.

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14-15 mpg on the highway isn't great but it will get better over time. You can install a tonneau to improve it a little bit if you don't already have one. You can also do a test: Drive a stretch of highway at 50-55 mph to see if it improves. That speed range is the most efficient for the AT4 and most vehicles for that matter.

Also, do you happen to live at a higher elevation?

AdamAT4 · March 28, 2020

14-15 mpg on the highway isn't great but it will get better over time. You can install a tonneau to improve it a little bit if you don't already have one. You can also do a test: Drive a stretch of highway at 50-55 mph to see if it improves. That speed range is the most efficient for the AT4 and most vehicles for that matter.

Also, do you happen to live at a higher elevation?

I drive the same highway often, anytime I leave town I do as I live in an isolated town with only 1 highway in and out, not big city here.

Trucks certainly burn more fuel at higher speeds, most limits are 60 to 70

Elevation is only about 1000 feet avg

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Osteoman · March 28, 2020

Thanks, maybe it needs to get broke in more.
Do you have a cover? I found my last gas truck made a small improvement on long trips with a tonneau.

I was expecting this truck to have a large fuel tank, I was pretty disappointed when I filled up.

The HD trucks have a 36 or 37 gallon I think.. it's over 130L anyway. Drive a solid 12 hours straight with that.

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I do not have a cover but was wondering the same thing, if it would improve a little. Logically it should.

I do not remember mine being worse in the beginning though. It just seems to have always gotten this. I do not tend to go over 70-73 max though on the highway.

Every truck is a little different but I would expect you to be doing a little better.

Btw. I have 24000 mi on it and so far it's been rock solid. No issues. I love it.

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Gthompson · March 28, 2020

I wish the tanks were larger so I don’t have to stop as much, but at least gas is cheaper than water!

zeon · March 28, 2020

At 75 and premium fuel I can get 19 to 20 at4 with Pirelli Tires At Plus at first it wasn't that good but at about 2000 miles it started to get better performance exhust. Just wondering if I add the gm performance air filter will it get bett