It's time to rev' up those engines once more sackfolk.
This lesson: start-line boost

Explaination based on 'r2 = gas, X = jump' controls (other controls will work the same)

During the 3,2,1 hold down 'gas' and 'jump' together, right as it changes to "go" let go of 'jump' while still holding 'gas'.
If you time it correct, you should be 'boosting of start'. With a little practise and timing and you'll be ahead of everybody.

Hope this helps.

Start burning those track up.