CREATE TABLE table_4638 ("Round" FLOAT, "Name" TEXT, "Circuit" TEXT, "Date" TEXT, "Winning driver" TEXT, "Winning car" TEXT)

Which driver drove car McLaren M23 at the Snetterton Circuit?
SELECT "Winning driver" FROM table_4638 WHERE "Winning car" = 'mclaren m23' AND "Circuit" = 'snetterton'
SELECT "Winning driver" FROM "table_4638" WHERE "Circuit" = 'snetterton' AND "Winning car" = 'mclaren m23'