Mack Defense Develops Hybrid-Electric Heavy Truck to Support U.S. Army Contested Logistics.

The U.S. Army is moving toward hybrid-electric heavy tactical trucks able to cut fuel demand, provide exportable electrical power, and support silent-watch operations during contested logistics missions. The American Company Mack Defense’s Common Tactical Truck (CTT) line-haul tractor prototype combines a high-voltage hybrid-electric powertrain with drive-by-wire controls and commercial-derived safety systems as the Army evaluates replacements for about 35,000 heavy trucks.

Mack Defense will display the 6×4 line-haul CTT tractor at the AUSA 2026 Annual Meeting and Exposition in Washington, D.C., from October 12 to 14, 2026, after prototype testing conducted to help the Army establish final requirements. The program is intended to improve logistics endurance, fuel efficiency, vehicle commonality, and electrical-power availability while reducing the sustainment burden across future heavy tactical truck variants.

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Mack Defense will showcase its hybrid line-haul prototype for the U.S. Army’s Common Tactical Truck (CTT) program at AUSA 2026 in Washington, D.C., highlighting fuel-saving hybrid-electric technology, exportable power, and next-generation heavy logistics capabilities. (Picture source: Mack Defense)

The line-haul tractor is a potential successor to trucks like the M915 series, which move heavy trailers long distances on highways and secondary roads. Based on the commercial Mack Granite truck, the prototype aims to combine commercial automotive technology with the durability, military integration, and sustainment requirements of Army logistics operations.

Hybrid-electric propulsion is one of the most operationally significant elements of the CTT (Common Tactical Truck)  prototypes. Mack Defense says all three trucks delivered under the prototype effort incorporate high-voltage hybrid-electric systems designed to reduce fuel consumption while allowing electrical systems to operate for extended periods without continuously running the diesel engine. The architecture also provides exportable electrical power for command posts, communications equipment, and other expeditionary loads.

Those capabilities could become increasingly important during distributed operations in which fuel convoys must travel longer distances and may face missile, drone, artillery, or ambush threats. Lower fuel consumption can reduce the frequency of resupply movements, while silent-watch operation allows communications, sensors, and other onboard electronics to remain powered with reduced engine noise and thermal output. Vehicle-generated power could also reduce dependence on separate generators and contribute to localized battlefield microgrids.

Mack Defense has built three principal CTT prototypes: an on-road tractor, an off-road tractor and a load-handling system truck. The company also developed designs for a cargo truck equipped with a material-handling crane, a recovery truck and a tanker, giving the Army a potential family of vehicles based around common components and a scalable architecture. Greater commonality could simplify training, maintenance and spare-parts supply while lowering lifecycle costs across the fleet.

The prototypes also introduce drive-by-wire technology, replacing or supplementing traditional mechanical control connections with electronically managed steering, braking and other vehicle functions. Mack Defense says the architecture supports collision avoidance, blind-spot detection, driver alerts, anti-lock braking, traction control and dynamic vehicle controls intended to mitigate rollover risks, while also creating a technical foundation for higher levels of automation.

Although the displayed tractor is not described as an operational autonomous vehicle, electronically controlled vehicle functions could allow the Army to integrate future automated driving or optionally crewed capabilities without redesigning the entire truck architecture. Such technology could be particularly relevant to high-risk logistics missions, where automated convoy functions may eventually reduce the number of soldiers exposed during resupply operations.

Mack Defense has also integrated a redesigned suspension intended to improve mobility and speed across rough terrain while retaining efficient road performance. This is significant for a line-haul tractor because Army logistics vehicles may have to transition rapidly from established highways to damaged roads, secondary routes, or unimproved operating areas.

Predictive-maintenance technology is another element of the CTT design. By monitoring vehicle condition and identifying potential failures before they produce breakdowns, the system is intended to improve availability and reduce unplanned maintenance, an important consideration for truck fleets expected to sustain high operational tempos over extended distances.

Cybersecurity and an open systems architecture are also incorporated into the prototypes. As tactical vehicles become more dependent on electronic controls, networked diagnostics, driver-assistance technology, and potentially autonomous functions, protection of onboard digital systems becomes increasingly important to both vehicle safety and mission reliability. An open architecture could also allow the Army to integrate new sensors, communications equipment, software or electrification technologies over the truck’s service life without replacing the entire vehicle.

Mack Defense received a U.S. Army contract to design, build, and deliver CTT prototypes for testing and evaluation. The current vehicles should therefore be regarded as developmental trucks supporting the Army’s requirements process rather than systems already selected for large-scale operational fielding.

The eventual CTT effort is intended to contribute to modernization and replacement of approximately 35,000 heavy tactical vehicles used across combat logistics, support, and service-support missions. At that scale, improvements in fuel consumption, parts commonality, maintenance requirements, and vehicle availability could generate substantial operational and sustainment benefits across the Army’s heavy truck fleet.

Mack Defense will present the hybrid line-haul tractor at booth 7501 during AUSA 2026 alongside other military-adapted commercial equipment. These include a Volvo Construction Equipment L120 wheel loader fitted with a fording kit for water depths up to 1.5 meters, a reduced-height split cab and air-transport tie-down and lifting provisions, a Volvo Penta D16 16.1-liter six-cylinder diesel engine, and a Prevost H3-45 motorcoach powered by a Volvo D13 engine.

For future U.S. operations, CTT's significance extends beyond replacing aging trucks. A heavy logistics fleet that requires less fuel, supplies its own electrical power, and shares more components across cargo, tanker, tractor, and recovery variants could reduce the logistical footprint needed to sustain deployed forces while improving readiness and operational endurance.

The combination of hybrid-electric propulsion, exportable power, predictive maintenance and electronically controlled driving systems also prepares the vehicle architecture for progressively more electrified and automated logistics operations. If these capabilities survive Army testing and are incorporated into the final CTT requirement, the program could change how U.S. forces move fuel, ammunition, equipment, and other heavy loads while operating under increasingly contested conditions.

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Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.