驰 is classical and rarely used alone in modern speech. It lives on in compounds: 奔驰 (gallop / Mercedes-Benz), 驰名 (renowned), 驰骋 (to gallop freely). The horse radical (马) reflects its original equestrian meaning.
The horse radical sits on the left - a horse with its tail and four legs compressed into three strokes in simplified form. It anchors the central meaning of galloping speed and indexes 驰 with the horse family: 骑 ride, 驾 drive, 骏 swift horse, 骄 proud horse.
也 is the phonetic, yě drifting to chí - a wide reading shift that still surfaces in 池 chí pond and 弛 chí slack. The same phonetic builds 她 she, 他 he, 地 earth - linked only by sound history.
