This paper analyzes the nature of vehicle handling in real-world situations and shows the importance of the driver. It introduces a new concept which provides a basis for quantitative determination of vehicle-handling qualities directly related to driver physical and mental efforts required for control of the vehicle. This paper focuses on ease of vehicle control and not on the level of vehicle performance as constituting the most important vehicle-handling quality.There is a description of rigorously designed subjective evaluation techniques employed in developing vehicle designs for determinations of ease of vehicle control. A new method is introduced to quantitatively determine the evaluator's ability to appraise the ease of vehicle control. Vehicle directional response properties affecting the ease of vehicle control are identified, and new criteria expressing these properties are introduced. Test procedures to measure relevant vehicle directional response properties are developed. Good correlation is established between measurements and subjective evaluation.