What term refers to the geometrical high point on the inside of a turn?

The term that refers to the geometrical high point on the inside of a turn is "apex." In driving and racing contexts, the apex is the point on the inside of a corner where the vehicle is closest to the edge of the track. It is crucial for optimizing speed and maintaining control while navigating the turn. By hitting the apex correctly, drivers can maximize their speed coming out of the turn, as this point allows for a smooth transition from steering to accelerating.

The other terms, while they may have geometric connotations, do not specifically relate to a turn in the context of driving. "Vertex" often refers to the point where two lines meet, primarily used in polygons or angle measurements. "Zenith" usually indicates the highest point in the sky relative to an observer or contextually, the highest point achieved. "Summit" refers to the highest point of a hill or mountain. These definitions do not align with the particular aspect of a turn in driving dynamics.