Instruction:
In autosports, what is the apex and racing line?

Response:
The racing line in autosports is an imaginary line in which when followed by the vehicle will provide the most efficient and quickest way through a turn or series of turns.  The apex of the racing line is the ideal point in which the car should be positioned closest to the inside of a curve.  The term, 'hitting the apex' is used when the ideal racing line is followed.