ST Engineering Land Systems is marketing the Terrex to potential buyers in Asia, South America and the Middle East.

[3] The initial AV-81 design utilised conventional coil-spring shock absorbers but later variants introduced of hydro-pneumatic struts with real-time damping control.

[10] On 18 July 2013, SAIC, along with ST Engineering Land Systems and Armatec Survivability Corporation, successfully completed two weeks of evaluations of the Terrex at Camp Pendleton.

The tests included a series of water performance demonstrations in various sea conditions and an evaluation of human factors and stowage capacity.

The Terrex completed all required surf transit and ocean swim maneuverability tests at its fully loaded combat weight.

It demonstrated load capabilities through successful stowage of gear and supplies that Marines would require for three days of operations, with space available for additional equipment.

The human factors evaluation demonstrated the spacious interior by accommodating the specified number of combat-equipped Marines and enabling rapid tactical and emergency egress through a quick-release hatch.

[11] The Marine Personnel Carrier was put on hold in June 2013,[12] restarted in February 2014,[13] and then restructured as Phase 1 of the Amphibious Combat Vehicle (ACV) program,[14] which includes the previous MPC competitor entries.

[16] On 24 November 2015, the Marines selected the SAIC Terrex, along with the BAE Systems/Iveco SuperAV, to move on to the engineering and manufacturing development phase of the ACV 1.1 program.

The vehicle uses a central tire inflation system, can swim 7 mph (11 km/h; 6.1 kn) in water, and has excess buoyancy of 23 percent.

[22] A further development of the Terrex 2, it is better protected and carries a much more powerful armament but lacks amphibious capability due to its 35 tonne weight.

The variant shown at the 2024 Singapore Airshow is the Trooper, utilizing ST Engineering's ADDER Remote Weapon Station, armed with a 30 autocannon that is likely a Mk44 Bushmaster II, as on the Hunter AFV.

In addition, the vehicle can be configured to carry varying combat payloads, from turret-based weapon stations (including 105 mm tank guns) to rocket launchers.

The Terrex AV-81 uses a patented independent double wishbone suspension, which greatly improves ground mobility and ride comfort over rough terrain.

The use of automatic traction control and the capacity for large footprint off-road tires enables it to travel at unprecedented speeds in soft ground conditions.