Next-Gen 2027 GMC Sierra 1500 AT4X Spied Testing – What to Expect

The 2027 GMC Sierra 1500 AT4X was spied testing alongside the Chevy Silverado ZR2 in Michigan. You can expect big changes for each of these trucks.

First Look: Sierra AT4X and Silverado ZR2 Caught on Camera

The next-generation 2027 GMC Sierra AT4X has been spotted testing around GM’s facilities in Michigan, offering the first real-world look at GM’s upcoming off-road upgrades. Spy photographers also captured the truck’s Chevrolet twin — the 2027 Chevrolet Silverado ZR2 — running on the same evaluation loop. Both prototypes wore heavy camouflage, but enough was visible to confirm that GM is working on major mechanical, interior, and capability improvements.

Key Exterior Upgrade: Room for 35-Inch Tires

A significant update for off-road fans is coming in the form of larger tire fitment. The current AT4X and ZR2 max out at 33-inch tires, a key disadvantage versus rivals like Ford’s Raptor and Ram’s TRX and RHO, all of which offer 35s from the factory. For 2027, GM is reshaping the front bumper and wheel openings to accommodate factory 35-inch tires. This change will improve ground clearance, approach angles, and overall off-road performance — addressing one of the biggest criticisms of the outgoing trucks.

Completely New Interiors for Both Trucks

Inside, both trucks are expected to receive full cabin redesigns.

• GMC Sierra: Will adopt a vertical touchscreen layout inspired by the GMC Yukon, along with higher-end seating and materials.
• Chevrolet Silverado: Will migrate to a horizontal display setup similar to the Chevy Tahoe.

These interior upgrades are aimed at resolving long-standing complaints about GM’s truck cabins, bringing them in line with the competition and improving comfort across all trim levels.

Powertrain Outlook: New V8s, Hybrids, and Carryover Engines

Under the hood, GM is preparing one of its most significant engine overhauls in years. Expected for 2027:

• Staying:
  • 2.7L Turbo High Output four-cylinder
  • 3.0L Duramax diesel
• Going away: Existing 5.3L and 6.2L V8s
• Incoming: Two all-new V8 engines, supported by an $888 million investment at GM’s New York engine plant.

GM has confirmed that the new V8s will include hybrid or plug-in hybrid technology, designed to meet the stricter 2027–2032 EPA emissions rules. These engines are expected to feature modern efficiency technologies such as cylinder deactivation, lightweight oils, auto start-stop, and potentially gasoline particulate filters.

GM is also investing an additional $300 million to upgrade its Michigan transmission plant, signaling ongoing refinement of its 10-speed automatic — including a new valve body to address previous rear-wheel lockup issues.

When will they debut?

Based on current development pace, the 2027 GMC Sierra and Chevrolet Silverado are expected to debut in spring 2026, with fall 2026 arrivals on dealership lots. Shoppers can anticipate:

• Updated exterior styling including revised bumpers and grilles
• Factory 35-inch tires on AT4X and ZR2
• Complete interior redesigns
• New V8s with hybridization
• Continued availability of the 2.7L Turbo and 3.0L Duramax
• Expanded use of the updated 10-speed automatic transmission

With major upgrades across capability, comfort, powertrain tech, and emissions compliance, the 2027 model year represents one of GM’s most comprehensive truck updates since 2018.