Racing line
The racing line is the fastest path through a corner — turn-in, apex, exit. The apex is the point closest to the inside of the corner, and hitting it well sets up a quicker exit.
Racing line — definition
The racing line is the fastest path through a corner — the geometry of turn-in → apex → exit that carries the most speed. The apex is the point where the car runs closest to the inside of the corner; clipping it at the right moment lets the driver straighten the wheel earlier and get on the throttle sooner for a quicker exit.
A good line is about the whole sequence, not one corner in isolation: sacrificing a little entry speed to nail the exit onto a straight is often faster overall. In sim racing, drivers refine the line using telemetry to compare laps corner by corner.
