CREATE TABLE table_63381 ("Model" TEXT, "Years" TEXT, "Engine code" TEXT, "Power" TEXT, "Torque" TEXT)

What is the engine code for the model xdrive35i?
SELECT "Engine code" FROM table_63381 WHERE "Model" = 'xdrive35i'
SELECT "Engine code" FROM "table_63381" WHERE "Model" = 'xdrive35i'