Mack MP13 Gets 2027 EPA Nod — More Power, Better MPG, B20 Approved
The 2027-compliant MP13 adds horsepower and fuel economy while waiting on EPA warranty-rule clarity that could cut thousands off the sticker.
When does the EPA 2027 MP13 start shipping?
Mack will open order books for the EPA 2027-compliant MP13 in August 2026, with production timed to model year 2028 vehicles. The engine will be available across Mack's highway and vocational lineup.
The 2027 MP13 delivers more power and better fuel economy than the outgoing version, though Mack has not yet published specific horsepower or MPG figures. The engine is now compatible with biodiesel blends up to B20 — up from B10 on the previous MP13 — and renewable diesel at R100 concentration, giving fleets added flexibility to incorporate lower-carbon fuels where available.
What the EPA warranty delay means for price
Mack, like every other engine maker, is still waiting on the EPA to finalize revisions to the 2027 emissions requirements. The agency previously announced that the emissions limits themselves would remain unchanged, but it is widely expected to modify or drop requirements for warranty and useful life that were projected to add significantly to the price of the new engines.
EPA at one time projected that rulemaking would happen in May, but Mack now expects it will be another three months. The warranty and useful-life provisions — if left intact — would extend coverage periods and durability testing beyond current standards, driving up both manufacturing cost and the retail price fleets pay per unit.
Until the EPA publishes the final rule, OEMs cannot lock in pricing or warranty terms for 2027-compliant engines. For fleets planning 2028 truck orders, that means spec'ing the MP13 without knowing the final delta between a 2027 engine and a 2024 or 2026 carryover unit.
Biodiesel compatibility and fuel flexibility
The jump from B10 to B20 biodiesel approval matters in states where biodiesel blends are mandated or where fleets have negotiated lower-cost B20 supply contracts. Running B20 in an engine approved only for B10 voids warranty coverage on fuel-system components — injectors, high-pressure pumps, seals — which can run into five figures on a Class 8 tractor.
R100 renewable diesel compatibility is less operationally complex than biodiesel because renewable diesel is a drop-in replacement for petroleum diesel with no blending limits and no cold-weather gelling issues. Fleets in California and Oregon, where R100 is more widely available, can run it without the fuel-system warranty risk that comes with exceeding a biodiesel blend ceiling.
What this means for 2028 truck orders
Fleets ordering Mack Anthem, Granite, or LR Electric models for 2028 delivery will have the option to spec the EPA 2027 MP13 starting in August. The engine's power and fuel-economy gains — once Mack publishes the numbers — will need to be weighed against the price premium, which remains unknown until the EPA finalizes the warranty rule.
For fleets that run biodiesel blends above B10 or have access to renewable diesel, the B20 and R100 approvals remove a fuel-system warranty barrier that existed on the previous MP13. That flexibility has real value in states with low-carbon fuel mandates or where renewable diesel is price-competitive with petroleum diesel.
The three-month delay on EPA rulemaking pushes final pricing and warranty terms into late summer or early fall, which compresses the window for fleets to evaluate TCO and lock in 2028 orders before production slots fill.
