Based on data from 55 vehicles, 4,063 fuel-ups and 1,461,770 miles of driving, the 2020 GMC Sierra 2500 HD gets a combined Avg MPG of 13.83 with a 0.12 MPG margin of error.

Any Engine Type 6.6L V8 DIESEL (48) 6.6L V8 GAS (7) Any Body Style Extended Cab Pickup (1) Crew Cab Pickup (16) Any Submodel SLE (4) SLT (6) AT4 (14) Denali (31)

Below you can see a distribution of the fuel-ups with 100 outliers (2.40%) removed.

Following shows the average MPG of each of the 55 vehicles in the system.

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• My Sierra 2500 HD

  2020 GMC Sierra 2500 HD SLE 6.6L V8 GAS Automatic 6 Speed
  Added Mar 2022 • 183 Fuel-ups

  Property of hoodsh

• 14.2 Avg MPG

• GMC Sierra 2500 HD

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Dec 2024 • 19 Fuel-ups

  Property of jdoug416

• 15.9 Avg MPG

• My Sierra 2500 HD

  2020 GMC Sierra 2500 HD SLE 6.6L V8 DIESEL Automatic 10 Speed
  Added Feb 2025 • 5 Fuel-ups

  Property of SpartacusADHD

• 16.4 Avg MPG

• 2020 Dmax

  2020 GMC Sierra 2500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Apr 2024 • 37 Fuel-ups

  Property of Bigboydmax

• 12.5 Avg MPG

• 2020 Sierra 2500 Duramax

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Dec 2019 • 289 Fuel-ups

  Property of mnoland2000

• 13.3 Avg MPG

• Gallo Negro

  2020 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added May 2022 • 35 Fuel-ups

  Property of doakman1

• 9.8 Avg MPG

• Granite AT4

  2020 GMC Sierra 2500 HD AT4 6.6L V8 GAS Automatic 6 Speed Crew Cab Pickup
  Added Oct 2020 • 198 Fuel-ups

  Property of NHATC

• 11.2 Avg MPG

• Sierra 2500HD Denali (Bertha)

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jul 2024 • 33 Fuel-ups

  Property of podnucmo

• 15.7 Avg MPG

• Neil GMC 2500HD

  2020 GMC Sierra 2500 HD SLE 6.6L V8 GAS Automatic 6 Speed Crew Cab Pickup
  Added Nov 2020 • 294 Fuel-ups

  Property of neilalvares

• 13.3 Avg MPG

• My Sierra 2500 HD

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Aug 2023 • 74 Fuel-ups

  Property of rlsudlow

• 15.1 Avg MPG

• My Sierra 2500 HD

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Aug 2022 • 89 Fuel-ups

  Property of jeepin13

• 14.2 Avg MPG

• GMC Sierra 2500 HD

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Aug 2024 • 16 Fuel-ups

  Property of josh021483

• 16.3 Avg MPG

• AT4

  2020 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Jul 2022 • 112 Fuel-ups

  Property of Dziuky

• 16.6 Avg MPG

• L5P

  2020 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Apr 2021 • 51 Fuel-ups

  Property of jwmontoya

• 13.6 Avg MPG

• Sierra 2500 HD

  2020 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Feb 2024 • 40 Fuel-ups

  Property of tdbreeding

• 12.5 Avg MPG

• GMC AT4

  2020 GMC Sierra 2500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2022 • 108 Fuel-ups

  Property of furlofoder

• 13.4 Avg MPG

• COVID Cruiser

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2020 • 235 Fuel-ups

  Property of jambiefsj

• 16.5 Avg MPG

• DenaliMAX

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Feb 2025 • 231 Fuel-ups

  Property of pauldnc

• 12.7 Avg MPG

• 2020 Denali 2500 HD

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2020 • 165 Fuel-ups

  Property of maaiman

• 16.0 Avg MPG

• My Sierra 2500 HD

  2020 GMC Sierra 2500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jan 2020 • 114 Fuel-ups

  Property of zardoz5

• 14.5 Avg MPG

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