2025 Chevrolet Tahoe Z71 and Suburban Z71 will offer updated diesel

Chevrolet added a diesel option to the new-generation 2021 Tahoe and 2021 Suburban, the first time the full-sizers had the option of an oil-burner since 1999. Chevy's chief engineer for the SUVs told Autoblog at the time, "It really came down to us giving customers a lot of choices. We know the SUV buyer is looking for this opportunity." Not long after the debut, we learned the Z71 wouldn't offer the turbocharged 3.0-liter inline-six Duramax diesel. Available as an option on every other trim, the Z71-specific front fascia designed to improve the SUVs' approach angles interfered with the oil-burner's intercooler and plumbing. That remains the case with the 2024 Tahoe and Suburban, and in the automaker's press release for the refreshed 2025 SUV siblings, we got info about the upgraded diesel but nothing about a trim expansion. All the automaker had to say was, "The new diesel engine will be available in 2025 after initial launch." GM Authority spoke to a Chevy exec who confirmed that whenever the diesel is open to order, the Tahoe Z71 and Suburban Z71 will offer it.

This is the same engine upgraded for the full-size pickup line and reaching into more trims on the truck side, too; the 2024 Silverado ZR2 added the Duramax for the first time, making it the entry-level engine and lowering the base price.  

The compression-ignition engine is updated with the same improvements GM made for its full-size pickup lineup recently. Refinements like a revised turbo compressor, retuned air induction system, higher-flow fuel injectors, steel pistons replacing taller aluminum pistons, revised piston-cooling oil jets, and finer thermal management pushed output to 305 horsepower and 495 pound-feet of torque, increases of 28 and 35 respectively. 

To make it fit into the off-road-focused Z71, engineers and designers reworked packaging of components in the front end and installed a skid plate that leaves more room for the diesel's intercooler and plumbing. From the outside, we can't see obvious physical changes when comparing photos of the 2021 Tahoe Z71 to the 2025 version, we'll have to get under the hood when the trucks arrive.

The diesel makes cases for itself on-road and off-road. On the trail, even though its 495 lb-ft. arrives at 2,750 rpm, it delivers 460 lb-ft at 1,500 rpm — the same peak torque as the previous diesel at the same rpm. The 6.2-liter achieves the same torque figure, but not until 4,100 rpm. The diesel twist is brilliant when the driver wants to let the SUV walk itself through a stretch of trail. 

Then there's the fuel economy. The EPA rates the outgoing diesel in the Suburban at 20 mpg city, 26 mpg highway and 23 mpg combined on four-wheel-drive models, rear-wheel-drive versions doing better by 1 mpg. V8 Suburbans muster 15/19/17 with the 5.3-liter engine and 4WD, while the uplevel 6.2-liter mill achieves 14/19/16 mpg ratings. For further comparison, the four-wheel-drive 2020 Ford Expedition Max gets 16/21/18 with its twin-turbo V6.