A correlation between engine dynamometer- and vehicle-aged catalysts has been established for novel lean-burn applications. A lean-burn, 1.8-L Ford Mondeo with a close-coupled three-way catalyst and an underfloor lean-NOx trap was used for this study. Vehicle aging of the emissions control system was done using a prescribed driving schedule. Engine dynamometer aging was done using a four-event aging cycle modified for lean-burn applications. The two aging methods were compared using maximum NOx conversion efficiencies measured during a two-mode dynamometer evaluation cycle. It was found that 75 h of four-event dynamometer aging is equivalent to 80,500 km of prescribed vehicle driving.