This paper describes the process which uses a parametric model to predict the contribution of vehicle noise sources to the total vehicle drive-by noise. The inputs to the model can be system target, CAE or test data. An initial model can be updated with latest system data throughout a vehicle program. The paper describes system and vehicle airborne noise procedures which have been developed due to the complexities of analysing system contributions to vehicle exterior noise during a drive-by test. The paper includes validation results and describes applications of the process which has proven to be the key to understanding how to set compatible vehicle drive-by noise and system noise targets.