GM's 2.7-liter Pickup Engine Comes Up Short in Real-world MPG Test

You’ve read no shortage of commentary about General Motors’ new truck engine on these digital pages — from the 2.7-liter four-cylinder‘s impressive on-paper power figures (310 hp, 348 lb-ft), to the continuing rivalry between GM and Ford, to the rather slim fuel economy gap separating it from its eight-cylinder stablemates. You’ve also read about GM’s reluctance to mention that the engine is, in fact, a four-cylinder.

Now, two real-world tests prove that your mileage may indeed vary — and 2.7 Turbo owners might not be happy with the results.

Car and Driver claims its recent test of a 2019 Chevrolet Silverado RST double cab 4×4 left them wanting more. More MPGs, that is. In a run through a 200-mile, 75 mph highway course, the 2.7-liter pickup not only fell below the vehicle’s EPA rating, it also returned worse fuel economy than a similar model equipped with a 5.3-liter V8 performing the same test.

Worse still, the 2.7-liter tied the gas mileage returned by a truck powered by GM’s revered 6.2-liter V8.

While GM’s 5.3- and 6.2-liter V8s recently saw the addition of cylinder-juggling Dynamic Fuel Management, the 2.7-liter’s combination of small displacement, turbocharging, and a host of fuel-saving measures conspires to return an EPA combined rating of 20 mpg in the particular truck tested by Car and Driver, compared to the 5.3-liter’s 18 mpg. On the highway, both trucks rate a 22 mpg figure.

In a high-speed highway slog that didn’t line up with the EPA’s more tepid testing cycle, C&D discovered that the “2.7T averaged 18 mpg over the 200-mile test, a 28 percent drop from the 21 mpg we observed in the 5.3-liter RST Crew Cab, which was a full 314 pounds heavier.”

The publication notes that, at 75 mph, the 2.7’s turbo was likely online, helping push the wall-faced Silverado through the resistant atmosphere. At a lower speed, like that seen in an EPA test, it’s likely the engine’s turbocharger would sit idle, returning the operator a higher MPG figure.

“Despite its 6.2-liter V-8 having more than twice the displacement and 110 additional horsepower—it also gets a 10-speed automatic rather than the 8-speed—the Denali managed to tie the 2.7T’s 18-mpg HFE result,” the publication noted. “The only half-ton pickup we’ve tested that has done worse on the HFE test is a 2017 Toyota Tundra SR5 fitted with the TRD Off Road package. It got 17 mpg.”

It also noted that a test of the Ford F-150 Raptor returned a result identical to the 2.7-liter GM product. It’s too bad the publication didn’t state what the temperature was during the two Silverado tests, as lower air temps reduce a vehicle’s fuel economy to some degree. The same goes for the other tested vehicles. We don’t know exactly where C&D tested these vehicles and on what day.

Still, recording significantly worse mileage in a four-cylinder versus a V8 is a jarring event, and one that might provide food for thought for prospective GM truck buyers.

[Images: General Motors]