This isn’t the first time General Motors introduced a diesel engine to their half-ton lineup: In 1994, GM put a 6.5-liter Detroit Diesel V-8 in the Chevrolet Tahoe which trickled down to other models including the Hummer H1 and GMC Yukon. Fast forward to today, a 3.0-liter inline-6 Duramax option is available in the 2021 Tahoe, Yukon, and Escalade that makes more power on fewer cylinders while almost doubling the EPA’s 1994 Yukon Diesel fuel-economy result. Surprising right? We got the chance to take the new GMC Yukon diesel out for a drive to measure real-world fuel economy and find how it compares to the petroleum options. Naturally, the subjective and technical results of our GMC Yukon mpg test were quite surprising for a full-size, three-row SUV!
After the 100-mile test loop, Charlie found the 2021 GMC Yukon Diesel mpg on the highway to come out to an average of 28 miles per gallon. This beats the EPA’s result of 26 mpg for a similar four-wheel-drive Yukon by two whole mpg, which means we can add this luxury SUV to our list of Daily Motor highway fuel economy overachievers. Charlie also found this little Duramax to be a smooth little hauler with plenty of torque. While the gas and diesel engines make the same amount of torque, maximum twist is available lower in the rev range with the diesel. You can expect this highway fuel economy claim to mirror the Chevy Tahoe mpg and Cadillac Escalade mpg when equipped with the same engine since most differences between the three are cosmetic.
Given the size of the 2021 GMC Yukon’s diesel tank at 26 gallons, if ran to empty the Yukon Duramax will travel 720 miles; chances are you’ll be desperate for a bathroom break by then. For comparison, the 6.2-liter V-8 achieved 19 mpg of petroleum during our testing which, depending on where you get it, is usually more expensive at the pump. If diesel engines weren’t so expensive of an option, and their reputation untarnished by other manufacturers, would they be more popular among American families?
How We Test the 2021 GMC Yukon Fuel Mileage:
Daily Motor’s real-world test of the 2021 GMC Yukon Diesel mpg consists of over 100 miles of consistent highway driving. We fill the 2021 Yukon Duramax using the “three-click method,” meaning running the gas pump on high flow until it clicks, waiting 10 seconds, running low flow until it clicks again, waiting another 10 seconds, then running low flow one final time. We use the lowest-octane fuel accepted by the vehicle’s manufacturer. We then drive 50 miles on public highway in one direction and then back in the opposite direction, attempting not to draft or accelerate hard. We set the cruise control at GPS-indicated 73 mph in an attempt to achieve a moving average speed of 70 mph over the entire test. Upon return to the fuel station, we refill the GMC Yukon Duramax at the same pump as the initial fill using the same three-click method to get an accurate reading of the GMC Yukon fuel economy. Miles per gallon is determined by dividing the total miles traveled by fuel used. In cases where our observed figure differs greatly from the 2021 GMC Yukon or Chevy Tahoe’s mpg EPA estimate, we may recommend a number in between or plan to retest the vehicle. Thanks for joining us in this test of the 2021 GMC Yukon Diesel’s gas mileage.