He is actually quite a good race car driver for a journalist (as, amongst other things, the 24 hour endurance race they did at Silverstone showed), but he drives so many different cars in so many different situations that he is always adapting his knowledge to the specific car he's in at the time. The other two are the same - it's the nature of their work.

Serious racing drivers (e.g. F1) know their own vehicle very very well and usually spend many hours before each race learning the track. Both of these were luxuries Hammond simply did not have.

Wade.