Based on data from 70 vehicles, 4,273 fuel-ups and 1,376,528 miles of driving, the 2021 GMC Sierra 2500 HD gets a combined Avg MPG of 13.17 with a 0.12 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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• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 GAS Automatic 6 Speed
  Added Jun 2021 • 183 Fuel-ups

  Property of gregnola

• 12.4 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2022 • 49 Fuel-ups

  Property of ryanhnicholson

• 11.5 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLE 6.6L V8 GAS Automatic 10 Speed
  Added Oct 2021 • 154 Fuel-ups

  Property of bdamats

• 2.8 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2022 • 36 Fuel-ups

  Property of gjonesy12

• 13.8 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2024 • 24 Fuel-ups

  Property of crossfamily

• 16.8 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD SLE 6.6L V8 DIESEL Automatic 10 Speed
  Added Jan 2023 • 112 Fuel-ups

  Property of Croybal06

• 13.6 Avg MPG

• AT4 Whore

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2021 • 156 Fuel-ups

  Property of pigpen23

• 12.4 Avg MPG

• DENALI 2021

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Dec 2020 • 120 Fuel-ups

  Property of rivcoinc

• 14.7 Avg MPG

• GMC Sierra 2500 AT4

  2021 GMC Sierra 2500 HD AT4 6.6L V8 GAS Automatic 6 Speed
  Added Mar 2022 • 90 Fuel-ups

  Property of 22GMCAT4HD

• 12.3 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Sep 2023 • 165 Fuel-ups

  Property of SeB21

• 17.1 Avg MPG

• 2021

  2021 GMC Sierra 2500 HD Denali Crew Cab Pickup
  Added Dec 2020 • 192 Fuel-ups

  Property of lampmant

• 13.0 Avg MPG

• My Sierra 2500 HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Apr 2023 • 89 Fuel-ups

  Property of bcfiremedic

• 12.1 Avg MPG

• 2021 Sierra 2500HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Jan 2024 • 52 Fuel-ups

  Property of Bost05

• 12.6 Avg MPG

• 21 Denali HD

  2021 GMC Sierra 2500 HD Denali 6.6L V8 GAS Automatic 6 Speed
  Added Apr 2021 • 46 Fuel-ups

  Property of shreff86

• 11.1 Avg MPG

• 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

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