Based on data from 63 vehicles, 3,497 fuel-ups and 1,119,642 miles of driving, the 2021 GMC Sierra 2500 HD gets a combined Avg MPG of 13.17 with a 0.13 MPG margin of error.

Any Engine Type 6.6L V8 DIESEL (45) 6.6L V8 GAS (17) Any Body Style Extended Cab Pickup (1) Crew Cab Pickup (14) Any Submodel Base (2) SLE (6) SLT (7) AT4 (21) Denali (27)

Below you can see a distribution of the fuel-ups with 11 outliers (0.31%) removed.

Following shows the average MPG of each of the 63 vehicles in the system.

• 1
• 2
• 3
• 4
• »

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2023 • 15 Fuel-ups

  Property of egobuster1

• 15.2 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Apr 2023 • 28 Fuel-ups

  Property of Jdcompman

• 15.9 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2021 • 138 Fuel-ups

  Property of xETERNALx

• 13.4 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Jul 2021 • 71 Fuel-ups

  Property of mkirbitz

• 16.3 Avg MPG

• Sierra 2500 HD aka Sully

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added May 2021 • 96 Fuel-ups

  Property of Ryot

• 12.2 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 GAS Automatic 6 Speed
  Added Aug 2021 • 44 Fuel-ups

  Property of drjim

• 11.7 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 GAS Automatic 6 Speed
  Added May 2021 • 194 Fuel-ups

  Property of Buellx72

• 11.4 Avg MPG

• 21 Denali HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 GAS Automatic 6 Speed
  Added Apr 2021 • 35 Fuel-ups

  Property of shreff86

• 11.1 Avg MPG

• GMC Sierra 2500 AT4

  2021 GMC Sierra 2500 HD AT4 6.6L V8 GAS Automatic 6 Speed
  Added Mar 2022 • 82 Fuel-ups

  Property of 22GMCAT4HD

• 12.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2022 • 32 Fuel-ups

  Property of gjonesy12

• 13.8 Avg MPG

• 2021 GMC Sierra Denali

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Feb 2024 • 4 Fuel-ups

  Property of chuckbench

• 13.2 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2022 • 39 Fuel-ups

  Property of ryanhnicholson

• 11.7 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Feb 2024 • 8 Fuel-ups

  Property of mstewart747

• 16.5 Avg MPG

• AT4

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Oct 2022 • 60 Fuel-ups

  Property of scrabble890

• 14.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLT 6.6L V8 GAS Automatic 6 Speed
  Added Jan 2021 • 31 Fuel-ups

  Property of NGreen08

• 10.5 Avg MPG

• AT4 DEF

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Dec 2022 • 6 Fuel-ups

  Property of scrabble890

• 717.6 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Aug 2023 • 12 Fuel-ups

  Property of bgeisick

• 16.7 Avg MPG

• 2021 2500HD Denali

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Apr 2021 • 115 Fuel-ups

  Property of DP68

• 17.2 Avg MPG

• 2021 Sierra Denali HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Feb 2021 • 118 Fuel-ups

  Property of ccc2511

• 16.1 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2020 • 90 Fuel-ups

  Property of russellruetz

• 13.7 Avg MPG

• 1
• 2
• 3
• 4
• »