Objective and subjective evaluations of additive structural modifications for a single automobile were used to determine the effects on structural feel and ride pleasability. The objective evaluations utilized modal analysis and frequency response function (FRF) measurements. FRF measurements were made on a 4-Post road simulator. Subjective evaluations were made by riding in the vehicle during 4-Post road simulator testing with pure roll, pitch, and twist inputs.The vehicle underwent six levels of additive structural modifications. Modal analysis, FRF measurements on the simulator, and simulator subjective evaluations were done for the baseline case, and were repeated following each modification. The modal analysis results indicated changes in the natural frequencies and mode shapes. The 4-Post road simulator results indicated objectively, with subjective correlation, whether, and by how much, the modifications improved the structural feel and ride pleasability of the automobile.