GMPartsGiant.com offers the wholesale prices for genuine 2016 Cadillac CT6 parts. Parts like Audio System are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 4 Cyl 2.0L, 6 Cyl 3.0L, 6 Cyl 3.6L. Model Code: 4 DOOR SEDAN, BASE 4 DOOR SEDAN, PLATINUM 4 DOOR SEDAN, PREMIUM 4 DOOR SEDAN.