This paper proposes an improved driving skill metric incorporating car-track deviation angle and car position off-set correction agility. The main advantage of the method is which it provides more accurate since this research is using more variables in the formulation for the skill metric compared to the old metric by using the same sample group of subjects. This paper reports nearly an average of 95% of improvement for the new skill metric estimation accuracy. The analysis further reveals the metric also has better driving skill index estimation consistency. The proposed method herein offers a means for characterizing driving skill in response to car-track input information and improving the intelligent behaviours of car support system