This paper describes an experimental method used to determine the aeroacoustic noise produced by a 'roof rack' placed on the roof of a vehicle. Testing was done on a vehicle roof positioned at the outlet jet of a small low-noise wind tunnel. A 'simulated vehicle cabin' was constructed beneath the vehicle roof that had similar absorption characteristics to an actual vehicle cabin. Sound pressure level measurements were made within the simulated vehicle cabin. The sound pressure level measurements were consistent with measurements made within the cabin of an actual vehicle in a large anechoic wind tunnel. The method could also be used to determine the in-cabin aeroacoustic noise produced by other vehicle accessories.