Based on data from 70 vehicles, 4,281 fuel-ups and 1,379,330 miles of driving, the 2021 GMC Sierra 2500 HD gets a combined Avg MPG of 13.17 with a 0.11 MPG margin of error.

Any Engine Type 6.6L V8 DIESEL (51) 6.6L V8 GAS (18) Any Body Style Extended Cab Pickup (1) Crew Cab Pickup (17) Any Submodel Base (2) SLE (7) SLT (10) AT4 (22) Denali (29)

Below you can see a distribution of the fuel-ups with 20 outliers (0.47%) removed.

Following shows the average MPG of each of the 70 vehicles in the system.

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• Sierra 2500 HD aka Sully

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added May 2021 • 112 Fuel-ups

  Property of Ryot

• 12.0 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 GAS Automatic 6 Speed
  Added Nov 2021 • 151 Fuel-ups

  Property of Danm1228

• 11.7 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jul 2024 • 18 Fuel-ups

  Property of josterhout1

• 16.3 Avg MPG

• 2500Hd GMC

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added May 2021 • 145 Fuel-ups

  Property of jmgolden1978

• 14.0 Avg MPG

• 2021 GMC Sierra 2500 HD

  2021 GMC Sierra 2500 HD 6.6L V8 GAS Automatic 6 Speed
  Added Mar 2021 • 72 Fuel-ups

  Property of Hay_Man_40

• 11.3 Avg MPG

• GMC AT4 - 21

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Sep 2024 • 3 Fuel-ups

  Property of Landmans

• 15.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLT 6.6L V8 GAS Automatic 6 Speed
  Added Jan 2021 • 245 Fuel-ups

  Property of kbeazley

• 10.6 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLE 6.6L V8 DIESEL Automatic 6 Speed
  Added Apr 2023 • 248 Fuel-ups

  Property of mcgr0401

• 13.0 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Jul 2024 • 5 Fuel-ups

  Property of jbhardman

• 13.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2020 • 108 Fuel-ups

  Property of mbrent77

• 15.6 Avg MPG

• GMC

  2021 GMC Sierra 2500 HD SLT 6.6L V8 DIESEL Automatic 6 Speed Crew Cab Pickup
  Added Apr 2023 • 31 Fuel-ups

  Property of Shire6

• 18.4 Avg MPG

• Big Bubba. My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2021 • 107 Fuel-ups

  Property of moose57

• 16.6 Avg MPG

• AT4 DEF

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Dec 2022 • 10 Fuel-ups

  Property of scrabble890

• 681.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2023 • 24 Fuel-ups

  Property of egobuster1

• 15.0 Avg MPG

• GMC

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Jul 2024 • 8 Fuel-ups

  Property of JK27

• 12.9 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2021 • 150 Fuel-ups

  Property of xETERNALx

• 13.4 Avg MPG

• BigTruck

  2021 GMC Sierra 2500 HD 6.6L V8 GAS Automatic 6 Speed Crew Cab Pickup
  Added Mar 2023 • 59 Fuel-ups

  Property of pmhanson

• 12.9 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLT 6.6L V8 GAS Automatic 6 Speed
  Added Jan 2021 • 40 Fuel-ups

  Property of NGreen08

• 10.3 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 GAS Automatic 6 Speed
  Added Aug 2021 • 53 Fuel-ups

  Property of drjim

• 12.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLE 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2024 • 8 Fuel-ups

  Property of fredc941

• 12.1 Avg MPG

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