The Elemental Driving Simulator (EDS) is a PC-based software and hardware system for advising people with known or suspected cognitive impairment. It is elemental in its simplicity and in its simulation of the elements of driving-related cognitive abilities. The EDS explicitly addresses metacognition and quantitatively relates it to performance. A neuropsychological case example, with an EDS Personal Report, is complemented by statistical findings from (1) working-age drivers (norms), (2) patients with central nervous system impairment seeking driver rehabilitation, and (3) a large sample of older drivers. The EDS proved to be a challenging procedure that all the normals completed more consistently, efficiently, and accurately than the other groups. Clinically, it discriminated extreme cases and, for those who fell in between, it helped focus the issues for further assessment and intervention. The discussion addresses how much realism is necessary, as well as the psychometric limitations of on-road testing.