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US diesel $4.049 per gallonWeek ending Aug 17, 2026 · EIA
SemiTrucks.org

Tractors

17 tractors, priced in fuel

Fuel economy here is a typical observed range for a loaded tractor at highway speed, not a specification. The same truck varies by more than a mile per gallon on gear ratio, tyres, speed and driver, and any single figure quoted for a model is marketing.

The last column is the one worth reading: what the difference from the most efficient truck in this list costs over 120,000 miles at $4.049 diesel. It is computed, not quoted.

Aerodynamic linehaul

9 models

Built around the drag equation. Every one of these is a set of compromises made in favour of fuel, and over 120,000 miles a year that is the right trade for almost everyone who is not choosing a truck on how it looks.

ModelYearsMPGWeightUsedFuel gap a year
Freightliner Cascadia

Freightliner

2017 to present7.2-917.0-19.5k$55-135k$1,445
Freightliner Cascadia (first generation)

Freightliner

2008 to 20176.2-7.416.8-19.0k$25-55k$12,913
Kenworth T680

Kenworth

2013 to present7-8.817.0-19.5k$50-130k$2,964
Peterbilt 579

Peterbilt

2012 to present7-8.817.0-19.5k$50-130k$2,964
Volvo VNL

Volvo

2018 to present7.4-9.217.2-19.8k$50-135k-
Mack Anthem

Mack

2017 to present6.8-8.517.5-19.8k$45-120k$4,974
International LT

International

2017 to present7-8.717.0-19.5k$35-110k$3,356
International ProStar

International

2008 to 20175.6-7.216.8-19.0k$18-45k$17,379
Western Star 5700XE

Western Star

2015 to 20237-8.617.5-20.0k$45-110k$3,753

Classic and long-nose

2 models

Set-back axles, long hoods, chrome and a great deal more drag. They cost real money in fuel and they hold their value in a way the aerodynamic trucks do not, which is a more rational argument for them than most owners bother to make.

ModelYearsMPGWeightUsedFuel gap a year
Kenworth W900

Kenworth

1963 to 20255.2-6.518.5-21.0k$35-180k$24,517
Peterbilt 389

Peterbilt

2007 to 20255.2-6.518.5-21.0k$45-200k$24,517

Regional and day cab

2 models

No sleeper, lighter, shorter wheelbase. Bought for payload and manoeuvring rather than for miles, and priced accordingly on the used market.

ModelYearsMPGWeightUsedFuel gap a year
Freightliner M2 106

Freightliner

2002 to present6.5-8.512.0-15.0k$30-90k$6,244
Volvo VNR

Volvo

2017 to present6.8-8.515.5-18.0k$45-110k$4,974

Vocational and heavy haul

4 models

Frames, axles and cooling built for weight and for work off pavement. Fuel economy is not the point and the specification sheet says so.

ModelYearsMPGWeightUsedFuel gap a year
Kenworth T880

Kenworth

2013 to present4.8-6.519.0-24.0k$55-165k$27,457
Peterbilt 567

Peterbilt

2013 to present4.8-6.419.0-24.0k$60-170k$28,225
Mack Granite

Mack

2001 to present4.5-6.219.0-25.0k$50-160k$32,279
Western Star 49X

Western Star

2020 to present4.6-6.319.5-26.0k$80-200k$30,613

Fuel gap is what the midpoint of each model’s range costs against the most efficient truck listed, over 120,000 miles at this week’s national diesel price, using the reciprocal relation rather than a straight difference. Used price bands are broad on purpose: condition, hours and remaining aftertreatment life move them further than the model does.