In this work a methodological approach for the analysis of the car driver's posture and of the seat performance and functionality is presented. It has been designed to integrate the information from the measurement of the driver's posture and anthropometry with the seat characteristics as described by shape and pressure map. The experimental protocol was applied on eight subjects.The data analysis allows for the definition of some new interesting parameters. An important result is the estimation of the relationship between pressure and interpenetration that represents a predictive model for pressure distribution from the anthropometrical data of the anatomical surface of the back. This should be confirmed by a wider analysis and it could lead to new instruments for the evaluation of seat prototypes.