Pursuant to a congressional request, GAO reviewed the Department of Transportation's (DOT) plans to develop a National Advanced Driving Simulator (NADS), focusing on: (1) how NADS will benefit the National Highway Traffic Safety Administration's (NHTSA) and the Federal Highway Administration's activities; (2) the projected capabilities of NADS compared with existing simulator capabilities; and (3) the estimated cost to develop NADS and the amount of non-DOT financial commitments. GAO found that: (1) although DOT believes that NADS research will benefit its programs, it cannot quantify NADS benefits in such terms as lives saved, dollars saved, and accidents avoided, since those benefits will accrue from new safety devices and designs; (2) NADS will have a more advanced visual system and a larger and more advanced motion system and will be able to carry out more research than existing driving simulators can; (3) simulation experts believe that the state of the art in simulation is such that there should be no technical risk associated with achieving the physical specifications for NADS; (4) after the design phase, NHTSA will be in a better position to judge whether there are technical risks and whether those risks can be overcome; (5) the $32-million estimate to develop NADS is uncertain since it has not been adjusted to reflect any future cost changes, and is based on a conceptual design that does not identify the specific equipment needed for NADS; (6) as of July 1992, NHTSA was not sure whether it would obtain financial commitments from non-DOT sources for one-third of the NADS cost before its planned design contract date; and (7) as of July 1992, NHTSA and the University of Iowa had not agreed on a plan for allocating NADS operating time among potential users, but the rights of DOT to use NADS would be covered in a cooperative agreement between NHTSA and the University.