The 2027 Chevrolet Silverado 1500 and GMC Sierra 1500 Get Worse Fuel Economy Numbers
The 2027 Chevrolet Silverado 1500 and GMC Sierra 1500 receive major updates, including new small-block V-8s, refreshed transmissions, and updated styling, but EPA fuel-economy ratings edge downward for most configurations compared with 2026. The 5.7L and 6.6L V-8s, now with larger displacements, generally reduce efficiency, while the 3.0L turbodiesel’s ratings also slide in many trims. The GMC Sierra AT4X with the diesel is the notable exception, posting gains in city and highway economy. Overall, the shift reflects a trade-off between power and efficiency, with final numbers varying by drivetrain and trim, and the 2.7L turbo-four ratings still to be published. Lookahead will hinge on EPA’s pending figures for that base engine.
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The 2027 models introduce updated small-block V-8 engines (5.7L replacing 5.3L; 6.6L replacing 6.2L) and revised transmissions, alongside refreshed exterior and interior designs.
EPA ratings show most powertrain–trim combinations delivering lower city, highway, and combined mpg than the 2026 counterparts, with the exception of the Sierra AT4X equipped with the 3.0L turbodiesel, which improves by up to 2 mpg on highway and combined cycles.
The diesel configuration retains a 3.0L displacement but can see as much as a 3 mpg drop versus 2026, a surprising outcome given its unchanged displacement.
Differences in mpg changes depend on drivetrain and trim, meaning the impact on fuel economy can be as small as 1–2 mpg or as large as several mpg in some 4WD diesel setups.
The 2027 Sierra AT4X with the turbodiesel stands out as the sole configuration with improved ratings among the lineup, while most other configurations see declines.
Final EPA figures for the 2.7L turbo-four are not yet published, keeping some uncertainty about the base engine’s efficiency relative to the prior year.