run fast
駛 centers on moving quickly, especially running fast. The idea is speed and swift motion.
駛 combines 馬 (horse) with 史, which likely contributes the sound and the idea of swift movement. The exact historical development of the right component is uncertain.
A horse 馬 beside a history 史 book: imagine a horse running so fast it races through history, leaving a blur of speed.
For シ, picture a horse running so fast it becomes a mere sheen of motion: sheen -> シ, and the horse speeds away.