The results of this pilot effort confirm the poor emission performance of relatively new, in-use passenger cars although 1977 and 1978 automobiles displayed better control than those prior to confirmatory testing at high altitude. The underhood inspections revealed that many vehicles had been subjected to various forms of maladjustments, primarily ignition timing and idle mixture. It was found that a resonable I/M program at high altitude would be effective in identifying higher emitters.