Based on data from 42 vehicles, 2,306 fuel-ups and 824,016 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 Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jul 2020 • 136 Fuel-ups

  Property of hotsauce8815

• 12.2 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 6 Speed
  Added Mar 2024 • 6 Fuel-ups

  Property of mlgriffin

• 15.8 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2020 • 152 Fuel-ups

  Property of fox454

• 15.1 Avg MPG

• My Denali

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed Crew Cab Pickup
  Added Mar 2020 • 109 Fuel-ups

  Property of cmayfield682

• 17.2 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2020 • 41 Fuel-ups

  Property of freedom2020

• 8.2 Avg MPG

• My Sierra 3500 HD #1

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Nov 2022 • 3 Fuel-ups

  Property of Blueyfella

• 5.7 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2022 • 26 Fuel-ups

  Property of s10stylez

• 15.2 Avg MPG

• My Denali 3500HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2021 • 43 Fuel-ups

  Property of williamsm5813

• 13.6 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Jan 2022 • 66 Fuel-ups

  Property of Grunnsetning

• 13.6 Avg MPG

• Big Booty L5P

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added May 2021 • 26 Fuel-ups

  Property of Bigbooty

• 10.8 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2020 • 29 Fuel-ups

  Property of Blueyfella

• 15.1 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Sep 2020 • 24 Fuel-ups

  Property of Camstyn

• 14.7 Avg MPG

• Sierra 3500 Denali HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Dec 2020 • 81 Fuel-ups

  Property of voylesjake

• 15.3 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Jan 2020 • 59 Fuel-ups

  Property of spence8870

• 15.9 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD SLT 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2021 • 24 Fuel-ups

  Property of chris129

• 14.7 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD 6.6L V8 DIESEL Automatic 10 Speed
  Added Jun 2021 • 3 Fuel-ups

  Property of trubluluder93

• 8.3 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Mar 2021 • 5 Fuel-ups

  Property of saulG96

• 13.4 Avg MPG

• Becca

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

  Property of Gunslinger4

• 16.5 Avg MPG

• AT 4 3500 HD

  2020 GMC Sierra 3500 HD AT4 6.6L V8 DIESEL Automatic 10 Speed
  Added Sep 2020 • 16 Fuel-ups

  Property of Jeferon1

• 12.1 Avg MPG

• My Sierra 3500 HD

  2020 GMC Sierra 3500 HD Denali 6.6L V8 DIESEL Automatic 10 Speed
  Added Nov 2020 • 9 Fuel-ups

  Property of aricb23

• 13.7 Avg MPG

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