GMPartsGiant.com offers the wholesale prices for genuine 2018 Buick Envision AWD parts. Parts like Engine Assembly & Partial Engine 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, 4 Cyl 2.5L. Model Code: 4 DOOR BASE, 4 DOOR PREMIUM, 4 DOOR PREMIUM 2, 4 DOOR UPLEVEL.