The serious point first, I am completely in favour of retesting for all drivers at all ages every 10 years, but accept it is impratical and will never happen.
The less serious, based on 800 hours cycling on the road each year (purely anecdotal and my own experience!). Some of the safest drivers in my area are taxi drivers and boy racers. I have a theory that the boy racer thing is that they get their kicks driving fast at 2am so during the day they drive very carefully!
Worst drivers are:
- Clarkson types, 50-70 year old men in beemers, jags etc. Close passes, no indicating, pulling out in front of you when they have clearly seen you approach. Note, not ALL 50-70 year olds, just a certain type hence the Clarkson reference 😉
-SUV drivers on the school run (usually female) also fall into this category.
-Anyone in a vehicle marked 'Highway Maintenance' (they are never actually official HM workers, they have just purchased old vehicles).
Older drivers are generally safe although can suffer from slower reactions and tend to delay pulling out when they have plenty of time, leaving it until it becomes a close call.