NO COMPROMISE IN QUALITY: While the market is being flooded with low cost (Asian) product, we feel that OEM quality is still the most important feature to bring to market. Engine Coolant Thermostat. This part generally fits BMW vehicles and includes models such as 325,325e,325es,325i,325is,325iX,525i,528e,535i,535is,635CSi,735i ,735iL,L6,L7 with the trims of Base Convertible 2-Door,Base Coupe 2-Door,Base Sedan 4-Door.