When you start the stage, hold X in the loading screen instead of spamming it. Hold it all the way you are about to rev up your car.

When you do an IL and fail something and wanna restart. You can press restart and do over. But the problem is that the start will not be as smooth as you 1st time load in the stage. There will be a delay when you launch the car. Simply just press return back to track and then you press select again and choose restart. Not only will you get a smooth start your car will restart back to start with a few centimeters ahead from the starting line. But this will cost your replay and the ghost car inputs as it will confuse the game.