The paper describes the development of a scale for the assessment of car interior sound quality.The scale had to meet three demands: Standardization, i.e. the scale values of different sound events should be directly comparable to each other. Economy; i.e. the use of the scale should be time efficient. Validity, i.e. the scale should be suitable for a precise distinction between sounds of different quality. A rating scale based on centile standards was constructed enabling the economic and specific measurement of four basic qualities: pleasantness, power, brightness and impulsiveness. In a series of experiments the scale was applied to a representative sample of interior sounds. The results show that the scale differentiates indeed precisely between the individual vehicles. This gives a reliable data base for the selection of reference sounds for optimization purposes.