2020 GMC Sierra 1500 Duramax Real-World Fuel Economy Test
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As you may already know, we spent a week behind the wheel of the 2020 GMC Sierra 1500, the new-generation truck that’s built on the GM T1 platform. Our test pickup’s key feature is the turbo-diesel 3.0L I-6 LM2 turbo-diesel Duramax engine. It’s rated at 277 horsepower and 460 pound-feet of torque and mated to the GM 10-speed automatic transmission which transfers power through either the rear wheels or optional 4WD.
One of the main reasons consumers might opt for the Duramax straight six instead of the two available 5.3L V8s (the 5.3L L82 V8 and the 5.3L L84 V8) or the 6.2L L87 V8 is better fuel economy. While diesel fuel tends to be slightly more expensive than gasoline (in North America, anyway), a diesel-powered truck can typically cover longer distances on a full tank. EPA fuel economy ratings for the 2020 GMC Sierra 1500 4WD with the Duramax I-6 are 24 mpg combined, 22 mpg city and 26 highway.
We took our truck out to see how those fuel economy figures stack up in real-world driving conditions. Since our tests were performed in Canada, the instrument cluster displayed fuel economy in L/100 km. However, we will gladly convert this to miles per gallon for you.
Each test was performed during a cool to mild Canadian spring, with temperatures ranging between 32 and 50 degrees Fahrenheit. The truck was unloaded, with only the driver on board, sending power to the rear wheels the entire time.
During our first route, we drove the 2020 GMC Sierra 1500 diesel through the city, with our route comprised of several stop and go situations. The second run was mostly performed during highway driving at a cruising speed of approximately 71 mph (115 km/h). The table below shows the real-world results we achieved during each run.
| Trip | Trip Distance | Average Speed | Recorded Fuel Economy |
|---|---|---|---|
| Trip 1 (Urban) | 45.8 miles / 73.8 km | 43 mph / 69 km/h | 20 mpg / 11.9 L/100 km |
| Trip 2 (Highway) | 66 miles / 106.3 km | 68 mph / 110 km/h | 25 mpg / 9.4 L/100 km |
| City | Highway | Combined |
|---|---|---|
| 22 | 26 | 24 |
Although we weren’t able to match GM’s official fuel economy numbers, these results are not that far off, and the cold(ish) weather in which we performed this test is yet another variable.
It’s also worth noting that, outside of actual fuel costs, another expense should be taken into account when figuring total cost of ownership is Diesel Exhaust Fluid, which the GM Duramax LM2 engine requires. Though a tank of DEF should last for several thousand miles, the amount used depends on the driving style, towing, loaded vehicle weight, weather and various other factors.
In addition, depending on the chosen 2020 GMC Sierra 1500 trim level, the turbo-diesel six costs between $2,495 and $4,980 more than the 5.3L L84 V8 with Dynamic Fuel Management, which boasts city/highway/combined fuel economy numbers of 16/22/19 mpg for 4WD models.
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What a cheap ass interior, the new one can’t come soon enough. To bad the Chinese flu delayed it by a year.
1. The interior is just fine.
2. It’s a human virus. Nothing to do with nationalism or country.
3. The plan was always to refresh the interiors for the 2022 MCE you giant bag of tools. Nothing was delayed or rushed.
It should be the Chicom flu, considering if Beijing had been a good world citizen and not tried to 1, cover it up, 2, incarcerated doctors trying to address the problem, 3 stop all Chinese travel to whuhan, yet retained travel from Wuhan to other countries-like they wanted it to spread. Beijing is to blame. cant change the past though.
@ stupid&awe
1. I agree but if it gets improved, well that’s good too.
2. Corona virus originated in C H I N A, that’s why people call it, “Chinese-virus,” “Kung-flu,” “China-flu” etc. It’s believed it came from some disgusting wet market located in Wuhan, C H I N A, others believe it came from some nearby (to wuhan) lab. But what we do know for sure is that the virus came from CHINA (chi-NAH!). There’s nothing wrong with saying that, just like there’s nothing wrong with saying other things that have its origin in its name like, Italian food, Mexican food, Chinese food, New York Times, Washington Times, etc.
3. ok.
Chinese virus.
But feel free to continue to be a social justice warrior.
In the mean time, the rest of the world will continue dealing with the virus that originated in China.
While not horrible, I too look forward to the new interiors.
Note they will be Tahoe / Suburban based to give you an idea what they will look like.
I doubt they will be identical, though…even though that’s not a bad thing.
Viruses are usually named after the region of origin or where they were first identified.
Ebola
Rocky Mountain Spotted Fever
West Nile
Covid-19 originated in the Wuhan area. China is and the puppets are too sensitive to allow Covid-19 to be referred to as a virus of Chinese origin.
While China was busy telling the world (including the WHO) that human to human transmission was impossible, they were also stockpiling PPE – in some cases importing from Europe and the US, who would later feel the wrath of this Chinese virus.
So screw their feelings.
And I loathe the fact that so many Americans, including our auto workers, have to lose work while we all stay stuck in our homes.
StupidAndAwe,Your screen name matches your comment. Typical idiotic liberal comment In regard to flu not coming from China.
Don’t be afraid to call a virus from China a Chinese virus.
It’s not racist or inaccurate. It’s just how it is.
If we’re afraid of the truth, then something is wrong.
It’s about as organic as Swillery’s smile
Interior is good and the layout and function is extremely good. What it is missing is a proper top trim interior, but if you consider those higher trims also come with a massive 8″ HD colour heads up display which internet warriors can’t see in photos, there is actually a lot of display real estate.. and again that HUD is extremely functional where as HVAC controls on say Ram’s touch screen is an annoyance.
Have you used Ram’s big screen? It has a ton of glare and for most touch inputs is worse that physical buttons. The 8.4″ Ram screen is the real interior you want if you don’t care about bragging and showing off. The 12″ is a showroom floor special, not a real world daily.
A metric gallon of gas is smaller then a US gallon 🙄
I got a sierra 1500 at4 duramax on mar 3rd of this year. By apr 4th, I was at 5500 miles driven. I have a bit of a heavy foot and drive fairly aggressively on maybe 90% highway miles(cruising 80mph – sometimes 90). I average 23mpg while carrying myself and about 750lbs of tools and other equipment(no towing).
Not very confident in any MPG meter in any vehicle. No mention of real world hand calculations. Would be more conclusive if done by hand, not relying on the meter. If you follow The Fast Lane Trucks, they top off before doing a long highway loop and hand calculate by refilling when done. Haven’t seen one MPG meter match the hand calculate results.
I know Steve, I’ve been driving a 2002 Silverado 2500 HD crew cab long bed Duramax for 18 years and love it. I drove it 214 miles at 85 mph once and got 20.6 mpg. Unbelievable for a 7500 lb vehicle. And I don’t have to use that Diesel exhaust fluid because it’s from before that came in.
If that’s the case, then this engine isn’t worth the extra money just for mileage.
What I want to know, was the re-gen in this model is used was it also calculated as part of the MPG or MPL of fuel. We all know re-gen kills the fuel mileage on ALL diesel motors, I know my ’16 drops from 13 or 14 down to 8.5 or 9 MPG.
gecko
Wonder how well that DIC is calibrated.
Having driven GM vehicles for the last 25years, and having tracked the accuracy of the reported mileage…….I’ve found that they are only accurate near a VERY small window. Most often they are accurate about 1/4 of the way between the low and high EPA numbers, then have veered as far as 30% off from there.
My current ’15 GMC Sierra is only accurate around 15mpg or so. That is the space where the actual gallons used divided by miles driven matches what the DIC reports. I’ve gotten as high as 22mpg on a single tank in this truck, and the DIC was reporting almost 26mpg on that tank. I’ve also towed through the hills and gotten around 10mpg actual with the DIC reporting about 7mpg. Have about 60k miles of data on this truck with actual and reported efficiencies logged if anyone wants to see them.
Would love to see what the ACTUAL numbers are, not what the REPORTED numbers are. The DIC isn’t consistently accurate enough to really trust IMO.
If this is a brand new truck, it may need more miles on it to get to it’s true mileage potential. Re-test it at 25k miles and results should be better.
Why do diesels get better mileage with more miles?
Yeah can we get an actual calculation? The DIC is nuanced, we need a gas station calculation where you put diesel in the truck record the amount of diesel it took . Do a loop, come back to the same gas station, fill it back up, record how many gallons it took, divide that by the amount you travelled, and that’s how you get a true number. I’m sure you’ve seen the TFL videos doing this.
Otherwise great work!
A more upright version of the Tahoe interior would be nice. Not sure if they can translate that center stack to a bench seat configuration, as some Silverados have.
Too bad they didn’t offer a manual transmission with that inline 6
Live to dream.. having the turbo-diesel 3.0L I-6 LM2 turbo-diesel Duramax engine. It’s rated at 277 horsepower and 460 pound-feet of torque and mated to the GM 10-speed automatic transmission which transfers power through either the rear wheels or optional AWD powering the Chevrolet Blazer RS AWD as this engine would be perfect for the 3-row configuration with all the hauling capability without needing to sacrifice fuel mileage.
Rain, snow, or slush on the road increases the vehicle’s rolling resistance, because in addition to moving the vehicle, the tires must also push their way through the precipitation on the roadway. The precipitation cools the tires, transmission oil and axle oils. These components operate less efficiently at lower temperatures. The increased rolling resistance and drive-train friction in just a light rain can increase fuel consumption by 0.2 to 0.3 mpg. – Freightliner.com
Here an example for those who can’t see the trees for the forest!
https://i.stack.imgur.com/aFee4.png
I drive a 19 GMC double cab with 6.2 and a 10 speed slt just filled up today with a16 mile round trip each way to work and home truck again got 20.5 mph, on the road the other day got 25.2 for a 220 mile trip, and it is a 4×4 truck
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A metric gallon of gas is smaller then a US gallon 🙄