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.
Colin McRae R4 Bonus Car
Finish in first place in all 66 events to get a 100% completion.
Cornering
Brake early, then increase the speed carefully when exiting a corner. In races where there are multiple opponents such as Rally Raid or CORR, position on left side if next turn is a left turn and vice versa. This will give you a much better chance of exiting a corner first or block your opponents from overtaking.
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.
Ending videos
Finish in first place in all 66 events to get a 100% completion to unlock two ending video sequence.
Increasing speed
To increase your maximum speed (stats), go for Hill Climb, Windy Point A, which is almost a long straight with some turns. Try using the Toyota Tacoma. To increase your average speed (stats), go for Hill Climb, Pikes Peak C (or BC) with a Toyota Tacoma.
Selecting a car
When choosing a car, look for torque rather than hp/tons. A high torque can overpower a car with more horsepower. The second best car is often more easy to handle than the most powerful one. You will often get cars as prizes. Try use them to the maximum before buying a new one (for example, if you do not win after ten attempts).
Acceleration...