During FY03, the U.S. Army Research Laboratory undertook a series of experiments designed to assess the maturity of autonomous mobility technology for the Future Combat Systems Armed Robotic Vehicle concept. The experiments assessed the technology against a level 6 standard in the technology readiness level (TRL) maturation schedule identified by a 1999 Government Accounting Office report. During the course of experimentation, 646 missions were conducted over a total distance of ~560 km and time of ~100 hr. Autonomous operation represented 96% and 88% of total distance and time, respectively. To satisfy the TRL 6 "relevant environment" standard, several experimental factors were varied over the three-site test as part of a formal, statistical, experimental design. This paper reports the specific findings pertaining to relevant-environment questions that were posed for the study and lends additional support to the Lead System Integrator decision that TRL 6 has been attained for the autonomous navigation system.