The associated data files are taken from data recorded under a NOx adsorber testing project at Oak Ridge National Lab (ORNL) during FY 2002. This particular test series was focused on measuring the performance of prototype NOx adsorbers installed in a Mercedes A170 1.7-liter diesel vehicle. Experiments were conducted with 5 candidate NOx adsorber monoliths (identified with labels A-E) to determine their emissions reduction performance as the air:fuel ratio and duration of the rich regeneration pulse were varied. Each prototype adsorber was installed downstream of a close-coupled diesel oxidation catalyst (at the turbocharger exit) and a catalyzed diesel particulate filter (CDPF).