The noise within a car interior affects the customers' perception of quality, hence the need for noise control in cars. The arrival of structural finite element analysis (FEA) and acoustic boundary element analysis (BEA) has created the possibility of quickly performing many computational design changes. Thus, effective noise control solutions can be predicted without many vehicle prototypes. Computational analysis of the passenger compartment of an existing four-door car was performed to predict and reduce road noise. This analysis guided the development of structural changes that would reduce the sound pressure levels at the driver's and rear passenger's ear locations. Laboratory tests of these structural modifications in a prototype vehicle confirmed that the sound levels were reduced.