CREATE TABLE table_22012 ("Name" TEXT, "Volume" TEXT, "Engine" TEXT, "Fuel" TEXT, "Output" TEXT, "Torque" TEXT, "Engine ID code ( s ) " TEXT, "0\\u2013100km/h , s" TEXT, "Top speed" TEXT, "CO 2" TEXT, "Years" TEXT)

Name the volume for co 2 for 168 g/km
SELECT "Volume" FROM table_22012 WHERE "CO 2" = '168 g/km'
SELECT "Volume" FROM "table_22012" WHERE "CO 2" = '168 g/km'