CREATE TABLE table_67324 ("Year" CLOB, "Driver/s" CLOB, "Class" CLOB, "Vehicle" CLOB, "Race title" CLOB)

What class of car had the XI Coppa Acerbo title?
SELECT "Class" FROM table_67324 WHERE "Race title" = 'xi coppa acerbo'
SELECT "Class" FROM "table_67324" WHERE "Race title" = 'xi coppa acerbo'