I do agree with what most of you guys have said, but......
I think you are forgeting one of the biggest things. It truely helped me take my driving up a level.
Consistantcy !!!!
If you have to drive a bit slower to keep it rubber side down, then do so. Sure some people are much faster, for a lap or two, but over the course of the race the person with the best average lap time wins.
Work on consistancy and avoiding those laps that are 10-20 above your average.
Speed only comes from experience ! Practice, practice, practice.... oh ya, and race when ever you can !!!!!!