Oil Companies Will Love That The 2027 Chevrolet Silverado's New V8s Get Worse Gas Mileage Than The Old Ones
Due to a litany of misguided decisions on behalf of the Trump administration, gas is ridiculously expensive right now, corporate fuel economy requirements are worryingly low, and we're in an affordability crisis. In totally unrelated news, the oil and gas companies that spent millions to elect Trump are raking in record profits that are more than double what they were at this time last year. Those oil companies are doing fine, but they will still likely be stoked to learn that GM announced the fuel economy numbers for V8-powered examples of the freshly redesigned 2027 Chevrolet Silverado today, and they all get worse gas mileage than the outgoing Silverado's V8s. These numbers should all also apply to the 2027 GMC Sierra, too.
According to documents posted by GM Authority, the fuel economy of all Silverados equipped with either the new 5.7-liter V8 or the new 6.6-liter V8 has dropped between 1 and 2 mpg across city ratings, highway ratings, and combined ratings. While these drops aren't especially significant, it's rare to see redesigned versions of cars debut with worse efficiency than their predecessors, even when we're talking about big trucks.
Consider the scale
2027 Silverados fitted with the 5.7-liter V8 are rated at 16 mpg city, 19 mpg highway, and 17 combined in two-wheel-drive form; opting for four-wheel drive drops both the highway and combined ratings by an additional mpg. Those city and combined figures are each down one mpg, and the highway rating is down two mpg compared to the 2026 Silverado.
Trucks with the 6.6-liter V8 are only shown in four-wheel-drive, and are rated at 14 mpg in the city, 18 mpg on the highway, and 15 mpg combined. If you go for the off-road-oriented Silverado ZR2, it drops the city and combined figures by 1 mpg and the highway figure by 3 mpg. (The same should go for the Sierra's AT4X equivalent.) All of those numbers are down by either 1 or 2 mpg when compared to their fuel economy ratings in 2026.
Even opting for the 3.0-liter inline-six turbodiesel powertrain option won't save as much fuel as it did last year. Most diesel-powered 2027 Silverados return between 1 and 2 mpg worse than last year, except for city mileage in some four-wheel-drive trims. City and highway mileage for the diesel ZR2 remains the same. Mileage ratings for the turbocharged 2.7-liter four-cylinder powertrain have not been published yet.
Considering that the Chevrolet Silverado almost always lands in the second-place spot on the list of best-selling vehicles in the U.S. behind the Ford F-Series, and the GMC Sierra isn't too far behind, the impact of small changes in efficiency get magnified. So far through the third quarter of 2026, GMC sold 252,639 Sierras and Chevrolet sold 413,383 Silverados, and production of the new-gen trucks only just started in October. Though not all of these trucks will be fitted with one of the new V8s, certainly a ton of them will, and decreasing even just V8 gas mileage by a single mpg will still result in a massive increase in collective fuel usage.