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Chevrolet Tahoe and Suburban diesel fuel economy is impressive for cars this huge

That straight-six Duramax oil-burner is estimated to return up to 28 miles per gallon highway in the smaller of these SUVs.

2021 Chevrolet Tahoe Suburban Diesel Fuel Economy - duramax mpg
The available Duramax diesel's fuel-economy scores have finally been released -- for two-wheel-drive models, at least.
Chevrolet/Craig Cole/Roadshow

As a rule, big, honkin' sport utility vehicles usually aren't that efficient. With curb weights greater than a main battle tank and the aerodynamics of a mountainside, you simply cannot expect Toyota Prius-rivaling economy. But proving you absolutely can teach an old dog new tricks, GM's latest crop of SUVs with the Duramax straight-six diesel delivers some shocking figures.

EPA certification for two-wheel-drive versions of both the Chevrolet Tahoe and Suburban are in, GM announced Wednesday. The Tahoe is officially rated at 21 miles per gallon in the city, 28 mpg highway and 24 mpg combined. Chevy's larger Suburban is only slightly less efficient, returning an estimated 27 mpg on the highway and 23 mpg combined. Around town, it should deliver the same score of 21. That is damn impressive fuel economy for what are basically dinosaurs -- comfortable and refined road-going reptiles, that is. Even better, because of the way diesels are tested by the EPA, it's likely the real-world fuel economy these vehicles deliver will be even better.

In comparison, a 2020, standard-length, two-wheel-drive Ford Expedition returns just 17 mpg city, 23 highway and 19 mpg combined. That's because it features a gasoline-burning 3.5-liter EcoBoost V6, a powertrain configuration that, for several reasons -- such as burning a less energy-dense fuel, greater pumping losses and a lower compression ratio -- is inherently less efficient than a diesel.

The 3.0-liter Duramax straight-six oil-burner in GM's new SUVs is less potent than Ford's EcoBoost V6, delivering 277 horsepower and 460 pound-feet of torque. That compares rather unfavorably to the Expedition's 375 hp and 470 lb-ft. Still, those figures should move the Suburban and Tahoe with relative ease and, of course, the stellar fuel economy is an upside that cannot be overstated.

There's nothing petite about the 2021 Chevrolet Suburban.

Craig Cole/Roadshow

When it comes to capability, a two-wheel-drive Tahoe with that diesel is rated to tow up to 8,200 pounds, while its maximum payload is 1,717. The bulkier Suburban can handle slightly less, 8,000 and 1,625 pounds, respectively.

Fuel economy scores for four-wheel-drive variants of these Bow Tie bruisers has not been released just yet, but check back early and often, because you can bet we'll publish those as soon as they come out.

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