DiRT

Increase your max. speed (stats):
Go for Hill Climb, Windy Point A, which is almost a long straight with
some turns. Try using the Toyota Tacoma.

Increase your average speed (stats):
Go for Hill Climb, Pikes Peak C (or BC) with a Toyota Tacoma.

CORR Rallys:
When doing the CORR Rallys, if the race has a bend first, wait until the
other cars have gone then accelerate. This will get you out of the pile
up at the first corner.

Acceleration
Accelerate about halfway down at the beginning. When you are familiar
with all tracks, accelerate hard on the straights and brake a good time
in advance before a turn.

Completion bonuses:
Finish in first place in all 66 events to get a 100% completion and
unlock Colin McRae R4 Bonus Car and two ending videos.