Braking before a turn ( or trailing-off in the turn ) is only necessary when the approach speed is higher than the entry speed. For a computer-driven car with

Braking before a turn ( or trailing-off in the turn ) is only necessary when the approach speed is higher than the entry speed. For a computer-driven car with accurate mapping, and hence foresight, it is more efficient to plan the approach so that no braking is necessary. After all, reducing cost requires efficiency rather than speed. Likewise on a long cycle ride I'll try to match the approach and entry speeds by easing-off rather than throwing-away calories by braking.