A Dynamic Motion Element for use in testing crash avoidance technologies in a subject vehicle, the Dynamic Motion Element comprising: a body comprising an upper surface wherein the upper surface is adapted to support a soft-body having the size and shape of a vehicle or a portion of a vehicle, the body having at least one tapered side so as to allow the subject vehicle to drive up to and on the upper surface with minimal to no damage to the subject vehicle or the Dynamic Motion Element, the body supported by a plurality of wheels; and a belt drive system for providing power to at least one of the wheels, the belt drive system comprising: a belt connected to a drive pulley and adapted to transfer power from the drive pulley to a driven pulley, the belt defining a belt plane and wherein the driven pulley is connected to at least one of the wheels; characterized by an articulating arm adapted to pivot about a pivot axis within the belt plane, wherein at the end of the arm is located the driven pulley that is also adapted to pivot about the pivot axis; and tensioner pulleys (1335, 1340) connected to the articulating arm adapted to pivot about the pivot axis, wherein the tensioner pulleys (1335, 1340) come in contact with the belt and are positioned such that it helps to maintain a near constant belt length throughout the allowable articulation stroke of the pivot axis. a body comprising an upper surface wherein the upper surface is adapted to support a soft-body having the size and shape of a vehicle or a portion of a vehicle, the body having at least one tapered side so as to allow the subject vehicle to drive up to and on the upper surface with minimal to no damage to the subject vehicle or the Dynamic Motion Element, the body supported by a plurality of wheels; and a belt drive system for providing power to at least one of the wheels, the belt drive system comprising: a belt connected to a drive pulley and adapted to transfer power from the drive pulley to a driven pulley, the belt defining a belt plane and wherein the driven pulley is connected to at least one of the wheels; characterized by an articulating arm adapted to pivot about a pivot axis within the belt plane, wherein at the end of the arm is located the driven pulley that is also adapted to pivot about the pivot axis; and tensioner pulleys (1335, 1340) connected to the articulating arm adapted to pivot about the pivot axis, wherein the tensioner pulleys (1335, 1340) come in contact with the belt and are positioned such that it helps to maintain a near constant belt length throughout the allowable articulation stroke of the pivot axis. a belt connected to a drive pulley and adapted to transfer power from the drive pulley to a driven pulley, the belt defining a belt plane and wherein the driven pulley is connected to at least one of the wheels; characterized by an articulating arm adapted to pivot about a pivot axis within the belt plane, wherein at the end of the arm is located the driven pulley that is also adapted to pivot about the pivot axis; and tensioner pulleys (1335, 1340) connected to the articulating arm adapted to pivot about the pivot axis, wherein the tensioner pulleys (1335, 1340) come in contact with the belt and are positioned such that it helps to maintain a near constant belt length throughout the allowable articulation stroke of the pivot axis.