The redesigned 2027 Chevrolet Silverado 1500 and GMC Sierra 1500 will offer improved long-distance capability for diesel truck owners, with a significantly larger Diesel Exhaust Fluid (DEF) tank on models equipped with the 3.0-liter Duramax diesel engine.
The upgrade will be paired with new 34-gallon extended-range fuel tanks, allowing drivers to travel farther between stops while sacrificing some interior storage space.
The changes reflect General Motors’ focus on improving towing convenience and highway range across its upcoming half-ton truck lineup. However, accommodating the larger tanks will require a significant change inside the cabin.
Larger DEF Tanks Bring Extended Range
The 2027 Silverado 1500 and Sierra 1500 will feature increased DEF capacity alongside the new 34-gallon fuel tanks.
For owners who use the 3.0-liter Duramax diesel for heavy towing, the additional capacity is expected to reduce the frequency of fluid refills and help minimize interruptions during long trips.
The diesel upgrade comes as GM prepares broader changes to its engine lineup, including larger-displacement options and higher prices for traditional gasoline-powered models.
2027 Silverado and Sierra Lose Rear Under-Seat Storage
The expanded tank capacity comes with a packaging trade-off.
Fitting both the larger DEF reservoir and the 34-gallon fuel tank beneath the trucks requires GM to eliminate the rear under-seat storage bins.
Those compartments have provided owners with concealed space for tools, emergency equipment and everyday belongings.
The change also means the redesigned trucks will have less cabin volume than the outgoing 2026 models.
Owners of the 2027 Silverado and Sierra will instead need to rely on the redesigned front center console, standard gloveboxes or aftermarket lockable bed boxes to store their belongings securely.
Diesel Range Takes Priority Over Cabin Storage
The larger DEF tank is aimed at drivers who prioritize long-distance towing and fewer stops during highway travel.
For fleet operators and private owners who regularly tow heavy trailers, increased fluid capacity could make extended trips more convenient by reducing the need to stop for DEF refills.
The loss of rear under-seat storage, however, represents a drawback for drivers who use their trucks for everyday family needs.
The 2027 Chevrolet Silverado 1500 and GMC Sierra 1500 will combine larger tanks with broader powertrain changes, while diesel buyers will need to weigh the added range against the loss of built-in cabin storage.
