One of the best guides as to which drivers are the worst is the insurance industry. As I understand it, the more costly your insurance, the more dangerous you're likely to be. On this basis, young men up to the age of about 25 are the most dodgy, and old ladies like me quite safe in comparison. My insurance is so low, they almost pay me to drive my little Fiesta. This is only a general, rough guide, as obviously some high insurances are due to the expensive and powerful vehicles driven. My point is, that the young lads are the ones who should have a watchful eye kept on them, and maybe a second test/assessment made after one year, say. Statistically, us oldies don't cause the most accidents.