As the compliance with noise legislation became more difficult, Ford exhaust system development engineers increasingly encountered variances not only from vehicle-to-vehicle, but on the same vehicle tested in different locations. As a result, a series of tests were conducted to establish the correlation among various sites for vehicle exterior noise measurements. The purpose of this paper is to present the results and the method developed to achieve the correlation in terms of the following: 1. Ford and site equipment differences 2. Driver differences 3. Differences between site physical qualities Seven sites were evaluated in the program where seven vehicles were used with a good spread in exterior noise levels.A representative correlation plot is also presented which can be used to predict the expected noise level of any vehicle at any one of these test sites knowing the level obtained at the Ford site. This paper also discusses the results of the analysis performed to determine the overall test repeatability for all sites, the test repeatability for each site and the repeatability of test equipment at various test sites.