Based on data from 42 vehicles, 2,307 fuel-ups and 824,345 miles of driving, the 2020 GMC Sierra 3500 HD gets a combined Avg MPG of 13.25 with a 0.16 MPG margin of error.

Any Engine Type 6.6L V8 DIESEL (40) 6.6L V8 GAS (1) Any Body Style Crew Cab Pickup (5) Any Submodel Base (1) AT4 (5) SLT (7) Denali (29)

Below you can see a distribution of the fuel-ups with 53 outliers (2.25%) removed.

Following shows the average MPG of each of the 42 vehicles in the system.

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• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2020 • 149 Fuel-ups

  Property of ghurd

• 14.3 Avg MPG

• 2020 GMC 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2020 • 387 Fuel-ups

  Property of Gassy1976

• 14.6 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 6 Speed
  Added Jul 2024 • 13 Fuel-ups

  Property of maddess00

• 17.6 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 GAS Automatic 6 Speed
  Added Jul 2020 • 86 Fuel-ups

  Property of jdmich

• 10.7 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jan 2020 • 7 Fuel-ups

  Property of Alec55

• 14.0 Avg MPG

• Star Lord vol. 2

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2021 • 40 Fuel-ups

  Property of rpar86

• 11.2 Avg MPG

• 2020 Sierra

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Jan 2023 • 105 Fuel-ups

  Property of brfs

• 15.9 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Jul 2020 • 183 Fuel-ups

  Property of abartlett

• 15.4 Avg MPG

• GMC Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Apr 2023 • 54 Fuel-ups

  Property of audiododd

• 13.8 Avg MPG

• Denali HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added May 2024 • 36 Fuel-ups

  Property of davijoh

• 11.8 Avg MPG

• 2020 3500 HD Denali

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added May 2024 • 23 Fuel-ups

  Property of bobsearle

• 13.8 Avg MPG

• Denali 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2021 • 115 Fuel-ups

  Property of 2010RWCM

• 13.6 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Apr 2024 • 11 Fuel-ups

  Property of Ranger473

• 13.0 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added May 2020 • 6 Fuel-ups

  Property of wedgie321

• 10.7 Avg MPG

• My Sierra 3500 HD Duramax

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Apr 2024 • 13 Fuel-ups

  Property of Bscherr

• 8.4 Avg MPG

• GMC

  2020 GMC Sierra 3500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Nov 2022 • 73 Fuel-ups

  Property of kitakidscomcastnet

• 14.4 Avg MPG

• GMC PlanetKiller

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2022 • 44 Fuel-ups

  Property of KyleMac

• 14.2 Avg MPG

• 2020 Def

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Apr 2023 • 14 Fuel-ups

  Property of brfs

• 380.6 Avg MPG

• Dee 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2020 • 283 Fuel-ups

  Property of deewhite

• 12.9 Avg MPG

• Damon’s Sierra 3500 HD Denali

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Feb 2020 • 293 Fuel-ups

  Property of Demon2JZ

• 11.2 Avg MPG

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