The invention, in at least one embodiment, relates to a reverse platinum group metal zoned lean NO.sub.x trap system included in a vehicle and its method of use. One embodiment of the trap system is in a vehicle exhaust system operable during lean and rich periods. The trap system may include a first trap having a first substrate supporting a quantity of platinum and a second trap, positioned downstream of the first trap, and having a second substrate supporting a quantity of platinum and a quantity of rhodium. The total loading of platinum plus rhodium on the second trap is greater than or equal to the platinum on the first trap. In at least one embodiment, the second trap has a higher overall NO.sub.x conversion at a low temperature and the first trap has a higher overall NO.sub.x conversion at a high temperature.