CREATE TABLE table_27085 ("Round" FLOAT, "Circuit" TEXT, "Date" TEXT, "Pole position" TEXT, "Fastest lap" TEXT, "Winning driver" TEXT, "Winning team" TEXT)

What date did Mike Rockenfeller have the fastest lap?
SELECT "Date" FROM table_27085 WHERE "Fastest lap" = 'Mike Rockenfeller'
SELECT "Date" FROM "table_27085" WHERE "Fastest lap" = 'Mike Rockenfeller'