CREATE TABLE table_16671 ("Rd." FLOAT, "Grand Prix" TEXT, "Date" TEXT, "Location" TEXT, "Pole Position" TEXT, "Fastest Lap" TEXT, "Winning Driver" TEXT, "Constructor" TEXT, "Report" TEXT)

Who was the winning driver on 13 August?
SELECT "Winning Driver" FROM table_16671 WHERE "Date" = '13 August'
SELECT "Winning Driver" FROM "table_16671" WHERE "Date" = '13 August'