S-MET Increment I (MUTT 8x8)

The US Army's robotic mule, the S-MET Increment I, is based on the eight-wheeled MUTT from General Dynamics Land Systems of Sterling Heights, Michigan. The hybrid-electric, swimming platform carries 1,000 lb (454 kg) of infantry equipment over 60 miles (97 km) in 72 hours and generates power for the squad – 3 kW stationary and 1 kW on the move.

Control modes include remote operation, a follow-me 'leash' and semi-autonomous functions, and the vehicle can be slung under a CH-47 helicopter. After 2019 trials with the 10th Mountain Division, 101st Airborne and 25th Infantry Division, fielding began in fiscal year 2021.

The first award in October 2019 was 162.4 million USD for 624 vehicles including support; a competitor's protest forced a new competition, followed by a hybrid contract worth up to 249 million USD for Increment I running to July 2025. Dividing 162.4 million by 624 gives roughly 260,000 USD per vehicle with training and support, so no clean unit price exists.

Casualty evacuation was not an original requirement: the Army added it in 2020 as an 'alternative method' after soldier feedback, without a dedicated stretcher module. Unlike the Mission Master SP - Rescue with its ready two-stretcher module, the S-MET remains first and foremost a load carrier that learned rescue on the job.