Loving the Baby Duramax - MPG

jonlsu · Jan 19, 2022

We just took a trip from Corpus Christi to New Mexico. Roughly 900 miles each way. In Texas I drove 90% of the way at 80 mph on cruise control. Avg mileage was 23.4 mpg. Once we got to NM, the speeds slowed down between 60-70 mph for the most part and I got right at 25 mpg. My trip computer was showing around .7 to 1 mpg less than what the hand calculation for mpg was showing.

Plenty of power for the mountains and driving in the snow was a breeze.

Had a couple of days where I woke up and it was around 8-10 degrees F outside. Cold Start took a few seconds longer than normal but it started right up.

Carmanjp · Jan 19, 2022

There definitely a cool smooth little engine you get the same torque numbers compared to the 6.2 but better fuel mileage and I’ll put mine in sport mode occasionally to mess around

zeeya · Jan 20, 2022

My last trip down from Lafayette to Cotulla TX. 485 interstate speeds and then the country roads for a few days. Loving this little diesel.

Regular Cab Duallies · Jan 23, 2022

jonlsu said:
We just took a trip from Corpus Christi to New Mexico. Roughly 900 miles each way. In Texas I drove 90% of the way at 80 mph on cruise control. Avg mileage was 23.4 mpg. Once we got to NM, the speeds slowed down between 60-70 mph for the most part and I got right at 25 mpg. My trip computer was showing around .7 to 1 mpg less than what the hand calculation for mpg was showing.

Plenty of power for the mountains and driving in the snow was a breeze.

Had a couple of days where I woke up and it was around 8-10 degrees F outside. Cold Start took a few seconds longer than normal but it started right up.

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Where in NM?

jonlsu · Jan 23, 2022

Regular Cab Duallies said:
Where in NM?

Angel fire and Taos.

Andystoy AT4 · Jul 19, 2022

2099 km/1312 (since new and about 1 month) miles fuel indicated is at 9.6l/100 km which converts to 24.5 mpg 80% highway with many stops and current trip about 300 miles @ 25.3 mpg/9.3 l/100. No fuel fills noted as my last fill was probably low because of an air lock, the pump filled very quickly. I should have a calculated after my next fill to see how it compares? I am down one mark on my DEF. Most of the highway speed is 103/64 mph with a small amount at 80/50 and a small amount at 112/70 mph,

2022 Refresh 1500 AT4 CC LM2 standard box with Retrax cover and Rhino Rb 20 steps stock.

Andystoy AT4 · Aug 21, 2022

Update on fuel mileage: 3281km/2051 miles indicated is at 9.4l/100 which converts to 25 mpusg. The screenshot is my most recent round trip: 450 km/280 miles and indicated is 7.7l/100 km which converts to 30.54 mpusg. The average speed shows 78.5km/hr which is about 49 m/hr. The first leg I got 7.6l/100 and the combination was 7.7l/100 which included a short trip to town, 2 cold starts and about 14 stop signs and 4 changes of direction on each leg of the trip. I had a combination of 20 miles(times 2) at 104 km/hr (65 mph) 20 miles (times 2) 85km/hr 53 m/hr and the rest at 96km/hr 60 mph.
The real difference seemed to come from dropping the speed from 65 to 60 mph. This is a 2 lane paved secondary road that has very little traffic but many changes in direction and some rolling hills, so this can't be compared to driving for 2 hrs on cruise and not stopping or changing direction. DEF is down one bar, oil is still at the full mark. The total weight in the truck was equivalent to 3 average adults.

Stock AT4 with no tune. Definitely impressed with the mileage on this last trip.

jonlsu · Oct 15, 2022

Went to Pensacola FL last week. Coming back I was in no rush. Put the cruise on 75mph from Pensacola to Corpus Christi.
From Pensacola to Houston I got 27.8 mpg.
Once I turned south from Houston I hit a headwind and dropped to 26.2.
That’s the best I’ve gotten on a long trip. Granted on the highway I normally always do 80.
That’s was hand calculation. The computer in mine always shows .8 to 1 mile less than what I really get.
Happy w that. Had 2 adults and 3 kids along w a bed filled to the bream.

2021 with about 20k miles