Real-world fuel economy ranges for every major Class 6–8 commercial truck. Figures represent highway-dominant operation under typical load; vocational applications reflect their respective duty cycles. Use these benchmarks to model operating cost, compare GHG21 vs. older equipment, or validate mpg claims when evaluating a used truck purchase.
Best long-haul mpg
10.5
mpg
Volvo VNL 860 D13TC (2021+)
Typical new sleeper
8.5
mpg
GHG21 Class 8 AMT
GHG17 sleeper
7.5
mpg
2017–2020 Class 8
Typical dump truck
5.5
mpg
Class 8 tri-axle vocational
| Make / Model | Typical MPG |
|---|---|
Freightliner Cascadia 126 2021+ | 8.5mpg |
Kenworth T680 Next Gen 2022+ | 8.5mpg |
Peterbilt 579 2021+ | 8.5mpg |
Volvo VNL 860 2021+ | 9.2mpg |
International LT Series 2021+ | 8mpg |
Mack Anthem 2021+ | 7.8mpg |
Western Star 49X 2021+ | 7.8mpg |
Freightliner Cascadia 126 2017–2020 (GHG17) | 7.5mpg |
Kenworth T680 2017–2020 (GHG17) | 7.5mpg |
Peterbilt 579 2017–2020 (GHG17) | 7.5mpg |
| Make / Model | Typical MPG |
|---|---|
Freightliner Cascadia 116 (day cab) | 7.2mpg |
Kenworth T680E (day cab) | 7.2mpg |
International LT (day cab, regional) | 7mpg |
| Make / Model | Typical MPG |
|---|---|
Any Class 8 Flatbed / bulk trailer | 7.5mpg |
| Make / Model | Typical MPG |
|---|---|
Mack / Kenworth / Peterbilt Tri-axle dump | 5.5mpg |
Kenworth / Mack / Western Star Front-discharge mixer | 4.5mpg |
Mack LR / International HX / McNeilus body Rear-loader refuse | 3.2mpg |
| Make / Model | Typical MPG |
|---|---|
Freightliner M2 106 | 10mpg |
International MV Series | 9mpg |
Kenworth T370 | 9.5mpg |
Peterbilt 348 | 9.5mpg |
Fuel is the second-largest variable cost in long-haul trucking after driver wages, typically running $0.45–$0.60 per mile at current diesel prices. The GHG21 generation of Class 8 sleepers — Freightliner Cascadia, Kenworth T680, Peterbilt 579, and Volvo VNL — achieves real-world highs of 8.5–10.5 mpg with full aero packages and predictive AMT calibrations. The Volvo VNL 860 with D13TC turbo-compound technology remains the segment leader. Older GHG17 trucks from 2017–2020 typically average 6.5–8.5 mpg on comparable routes, a gap worth roughly $6,000–$12,000 per truck annually at current diesel prices. Vocational equipment operates in fundamentally different duty cycles where aerodynamics matter less than engine torque, axle configuration, and PTO efficiency. Use the cost-per-mile calculator to model how mpg improvements affect your breakeven freight rate.
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A modern GHG21-era long-haul sleeper (post-2021 Freightliner Cascadia, Kenworth T680, Peterbilt 579) averages 7.5–9.5 mpg on highway routes. The Volvo VNL 860 with D13TC turbo-compound technology leads the segment at 8.0–10.5 mpg. Older GHG17 trucks from 2017–2020 typically see 6.5–8.5 mpg. Vocational trucks like dump trucks and concrete mixers average 3.5–6.5 mpg due to short cycles, grades, and auxiliary PTO loads.
GHG17 refers to the EPA Greenhouse Gas Phase 1 regulations effective for 2017–2020 model years. GHG21 (Phase 2, effective 2021+) required significant improvements in aerodynamics, powertrain efficiency, and tire rolling resistance. In practice, GHG21 sleepers from the same manufacturer gain approximately 0.7–1.2 mpg over their GHG17 predecessors on comparable long-haul routes — a meaningful operating cost difference at scale.
Yes significantly. Automated manual transmissions (AMT) consistently outperform traditional manual transmissions by 3–8% in real-world fuel economy, primarily because they shift at optimal rev points regardless of driver technique. AMT penetration in new Class 8 sleepers has exceeded 90% as a result. Allison automatic transmissions — common in vocational applications — are less efficient than AMT on highway but are better suited to stop-and-go cycles with hydraulic loads.
At $3.80/gallon diesel, the difference between 7.5 mpg and 9.0 mpg on a 130,000-mile/year truck is roughly $9,700 per year in fuel savings. For a 100-truck fleet, that spread is nearly $1 million annually. This is why GHG21 equipment commands a resale premium and why fuel economy is often the single most important spec when evaluating a used Class 8 purchase.
Vocational trucks operate in fundamentally different duty cycles than over-the-road trucks. Dump trucks, mixer trucks, and refuse trucks make short runs, idle extensively, climb grades with heavy loads, and operate PTO-driven equipment (hydraulic tailgates, drum rotation, packer mechanisms) that draws engine power directly. A concrete mixer can spend 30–50% of its engine-on time idling at a batch plant or job site, which destroys average fuel economy.
Aerodynamics dominate at highway speeds above 60 mph — a full integrated aero package (roof fairing, side extenders, chassis skirts, trailer tails) can improve mpg by 15–25% versus a non-aero spec. Below highway speed, powertrain efficiency (engine calibration, rear axle ratio, transmission shift logic) becomes more important. Tire rolling resistance is the third most impactful variable, worth 2–5% in real-world testing.