This Is The Diesel Engine Truck That Gets The Best MPG In 2025

Diesel powertrains have historically been associated with two things: big towing power and increases in fuel economy compared to their gasoline-powered counterparts. Diesel engines usually provide big torque numbers at low revs, so towing and fuel economy both benefit —  results that are particularly helpful in purpose-built vehicles like pickup trucks that tow regularly and need all the fuel economy help they can get. Smaller turbocharged gasoline engines are becoming much more popular these days, and they're available under the hoods of trucks in virtually every class, but there are still some diesel powertrains holding on. 

One engine in particular, the diesel engine that powers General Motors' workhorse pickup trucks, offers some pretty impressive fuel economy ratings. The engine in question is a turbocharged 3.0-liter inline six-cylinder diesel available under the hood of the Silverado 1500 and plush pickup siblings like the Sierra 1500 we recently tested. According to the EPA, the diesel-powered Silverado and Sierra can return fuel economy numbers of 26 mpg combined (23 city/29 highway), which is better than every gasoline-powered full-size pickup truck the EPA has rated for 2025.

The only truck that beats the diesel Silverado and Sierra twins is the compact Ford Maverick and its fuel-sipping hybrid powertrain. Even the midsize Toyota Tacoma with its hybrid powertrain can only muster 23 mpg combined in its most economical configuration. 

The 3.0-liter Duramax that powers the Silverado and Sierra 1500 twins puts out 305 hp and 495 lb-ft of torque, and it is paired with a 10-speed automatic transmission. It has enough grunt to tow over 13,000 pounds with either truck, so it seemingly has both the fuel economy and towing power covered.

However, there is a caveat: to get top fuel economy ratings with GM's diesel trucks, you'll need to go with two-wheel drive versions of the pickups, with minimal equipment. Off-road versions like the Trail Boss have much worse estimated mileage, thanks to heavy equipment and less-efficient all-terrain tires. A diesel Silverado 1500 with mud tires and four-wheel drive, for example, has an EPA estimate of 23 mpg combined, the same as an identically equipped Sierra. The ultra-capable Sierra 1500 AT4X drops even further, to 19 mpg combined.

It is also worth noting that the 3.0-liter Duramax is currently the only diesel engine with an official EPA rating, so the title of "best diesel MPG in 2025" loses a bit of its gravitas. No EPA-rated pickup trucks for 2025 come with diesel engines. Several heavy-duty trucks are available with diesel engines, but the EPA doesn't rate them. That said, heavy-duty trucks almost certainly return much worse fuel economy, even with their diesel powertrains — owners typically report ratings between 10 and 18 mpg with the 6.6-liter Duramax diesel engine, for example.