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The EPA gives each new pickup truck fuel mileage ratings for city and highway driving. But truck buyers are curious: How quickly do those mpg drop off while towing? And is a gas V8, turbocharged V6, turbodiesel, or hybrid the most efficient tow rig? Read on for the mpg each powertrain maintains while towing a trailer over one of the steepest passes in the Rocky Mountains–and how that compares to its regular mileage.

Does a turbocharged V6 or a V8 get better mpg while towing?

A 2WD F-150 with the Coyote V8 and one with a turbocharged V6 get fairly similar fuel mileage. While both trucks can handle a steep mountain pass with a heavy trailer, the V8 maintains better mpg. Going back down, the V8 is better at maintaining the load, requiring you to apply your brakes less often.

The Ford F-150 PowerBoost EcoBoost proves it is one of the most efficient pickup trucks for towing by pulling a camper up a mountain pass.
Ford F-150 towing | Ford

Ford’s positioned its turbocharged V6 engine as the economically and ecologically friendly option–even naming it the EcoBoost. But Ford F-150s with the 5.0-liter “Coyote” V8 and 3.5-liter EcoBoost V6 earned similar EPA fuel mileage ratings. The EcoBoost has better city mileage (18 mpg vs. 17 mpg), but the V8 pulls ahead on the highway (25 mpg vs. 24 mpg). The V8’s combined rating is 20 mpg, while the EcoBoost earns 21 mpg.

The reviewers at TFL Truck are Colorado-based, so they were able to take these two F-150s on a towing test over “Ike’s Gauntlet,” an 8-mile highway mountain pass with a 7% grade. They hooked both trucks to an 8,900-pound trailer. The V6 Ford reached the top a few seconds earlier but burned through 3.5 mpg. The V8 revved a bit higher, and was a few seconds slower, but maintained 4.0 mpg.

On the way back down, the reviewers needed to tap the EcoBoost truck’s brakes 11 times. But the V8 truck got away with nine brake applications.

Is the F-150 PowerBoost efficient while towing?

Ford upgraded its EcoBoost with an electric motor/generator sandwiched between its V6 and 10-speed automatic. The resulting F-150 “PowerBoost” truck makes 430 horsepower and 570 lb-feet of torque. It is a capable tow rig and as efficient as the V8-powered F-150 while towing.

A Ford F-150 pickup truck towing a boat down a remote road, trees visible in the background.
Ford F-150 towing | Ford

Here’s the shocker: When TFL Truck took the new F-150 “PowerBoost” hybrid over the Rockies, it only got 3.8 mpg on the climb. But wait, there’s more.

Because the PowerBoost churns out a whopping 570 lb-ft of torque, the team hooked it up to a 10,000-pound trailer and took it over the 10-mile Vail Gauntlet. It only got 3.8 mpg up to the top of the pass. But a hybrid truck’s secret weapon is regenerative braking. So on the way back down, its overall mpg came back up considerably.

Pulling the 10,000-pound trailer and doing a grueling 10-mile climb at 10,603 feet above sea level put the F-150 PowerBoost near its limit. The truck came so close to overheating that it went into limp mode for the tail end of the climb. But it finished the job.

Is a diesel half-ton truck an efficient tow rig?

Heavy-duty diesel pickup trucks are legendary tow rigs. For years, all the Detroit Three offered a turbocharged diesel in their half-ton trucks too, but the GMC/Chevrolet Duramax I6 is the last one standing. The Duramax, redesigned for 2023, is one of the most efficient tow vehicles available.

Closeup of the Duramax Turbo Diesel badge on a GMC Sierra 1500, one of the most efficient pickup trucks for towing.
GMC Sierra 1500 DuraMax Turbo Diesel badge | General Motors

When TFL Truck took a GMC Sierra 1500 with a Duramax I6 over Ike’s Gauntlet, the mpg results were impressive.

The team was also testing a camping trailer, so the GMC only had to pull 7,000 pounds through cool April weather. So the test gave no insight into the truck’s upper capacity. But its mpg was near the top of its class: 5.9 mpg up the pass.

The EPA gave this GMC a fuel rating of 24 city/29 highway mpg (26 combined). So while its 5.9 mpg mountain towing efficiency sounds impressive, it’s 22.7% of the truck’s combined mpg. Its efficiency is not much better than the F-150 V8: that truck’s 4.0 mpg was 20% of its 20 mpg combined efficiency. The Duramax is so efficient while towing because it is efficient while doing just about anything.

See how all of these half-tons stack up in the table below:

F-150 EcoBoost V6F-150 Coyote V8F-150 PowerBoost HybridGMC Duramax Diesel I6
Highway24 mpg25 highway25 mpg29 mpg
City18 mpg17 mpg25 mpg24 mpg
Combined21 mpg20 mpg25 mpg26 mpg
Ike’s Gauntlet3.5 mpg (8,900 lbs)4.0 mpg (8,900 lbs)3.8 mpg (10,000 lbs)5.9 mpg (7,000 lbs)
Towing Efficiency16.6%20%15.2%22.7%

Next, find out why the Tundra’s new turbo V6 and Ram’s old Hemi V8 get identical mpg or see the GMC 1500 with the Duramax’s towing tested in the video below: