SELECT "Winning driver" FROM table_28094 WHERE "Date" = 'April 11'
Who won the April 11 race?
CREATE TABLE table_28094 (
    "Round" real,
    "Circuit" text,
    "Location" text,
    "Date" text,
    "Pole position" text,
    "Fastest lap" text,
    "Winning driver" text,
    "Winning team" text
)