I'll talk about racing line. Racing Line is the specific position of the car on the road or turn that make the car go fastest thru the whole track. There are so many factors that make them difference:
Cars: FWD, AWD, RWD, FR, MR, RR, weight, suspension.......
Condition: Wet, Dry, Cold, Hot.
Track: Radius of the turn, the distance before and after then turn.
People write the whole book about it. Simple answer is the line to make the car go fastest.
