Tank figures are the manufacturer's rated capacity, sorted smallest tank first. The EPA doesn't rate fuel economy for heavy-duty pickups and vans (over 8,500 lb gross vehicle weight), so these trims have no official MPG or range.
What it costs to fill up a 2026 GMC Sierra 3500HD
$153.72to fill the 36.0-gallon tank from empty with regular, at this week's US average of $4.27 a gallon.
At 36.0 gallons, the Sierra 3500HD's largest tank ranks second of the three 2026 pickups compared here. The Ford F-350 Super Duty carries the most (48.0 gal) and the Chevrolet Silverado 3500HD the least (36.0 gal).
Picked by body style and size: other 2026 pickups within about 5% of the Sierra 3500HD's length and 15% of its curb weight, one model per brand.
2026 GMC Sierra 3500HD fuel system recalls
NHTSA lists 1 fuel-system recall for the 2026 GMC Sierra 3500HD, out of 2 recalls in total. A recall applies only to the vehicles named in it, so check your VIN.
General Motors, LLC (GM) is recalling certain 2025-2026 Chevrolet Silverado 3500, and GMC Sierra 3500 vehicles with gasoline engines and dual fuel tanks (RPOs L8T and N2N). The rear fuel pump may not transfer adequate fuel to the front tank, causing an engine stall.
Risk and remedy
Risk: An engine stall increases the risk of a crash.
Remedy: The vehicle's engine control module (ECM) will be updated by a dealer or through an over-the-air (OTA) update, free of charge. Owner notification letters were mailed April 8, 2026. Owners may contact GMC customer service at 1-800-462-8782 or Chevrolet customer service at 1-800-222-1020. GM's number for this recall is N262544420. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on March 5, 2026.
What is the fuel tank capacity of the 2026 GMC Sierra 3500HD?
The 2026 GMC Sierra 3500HD holds 36.0 gallons (136 liters) on every trim we list.
How many gallons and liters does the 2026 GMC Sierra 3500HD gas tank hold?
The 2026 GMC Sierra 3500HD tank holds 136 liters, or 36.0 gallons in US gallons.
Does the 2026 GMC Sierra 3500HD tank change with the powertrain?
No. Gas and Diesel versions of the 2026 GMC Sierra 3500HD use the same 36.0 gal tank.
Does 4WD change the 2026 GMC Sierra 3500HD gas tank?
No. 4WD and RWD versions of the 2026 GMC Sierra 3500HD use the same 36.0 gal tank.
What gas does the 2026 GMC Sierra 3500HD take?
Regular unleaded, or Diesel fuel, depending on the engine. The label inside the fuel door confirms it for your car.
How much does it cost to fill up a 2026 GMC Sierra 3500HD?
At the US average of $4.27 a gallon for regular (EIA, week of October 26, 2026), filling the 36.0-gallon tank from empty costs $153.72. It ranges from $133.20 in the Gulf Coast to $212.04 in California.
How much does a full tank of gas weigh in a 2026 GMC Sierra 3500HD?
About 252 pounds for the 36.0-gallon tank. Diesel weighs roughly 7 pounds a gallon.
Does the 2026 GMC Sierra 3500HD have a bigger gas tank than the Chevrolet Silverado 3500HD?
No, they match: both top out at 36.0 gallons in 2026.
Has the 2026 GMC Sierra 3500HD had a fuel pump or fuel system recall?
Yes. NHTSA lists 1 fuel-system recall for the 2026 GMC Sierra 3500HD: 26V129000 (delivery · fuel pump · control/drive module). Check your VIN at nhtsa.gov/recalls to see if your car is affected.
Sources
Tank sizes: manufacturer-rated capacities from US-market specifications, cross-checked against a second spec database. Updated October 2026.
MPG and range: EPA ratings. Range is tank size times EPA MPG.