Q: volkswagen polo engine cover purpose.

Yes, these covers to serve a cosmetic and functional purpose. One purpose is to cover up the workings of the engine in case water is to splash under the hood so the electrical components do not get too wet. Many engine covers have heat shielding that keeps the heat under the hood from damaging the paint under extreme conditions. Some vehicles engine covers are even working into the induction or crankcase ventilation system. In mot cases, if the cover is missing and there are no functional problems with the vehicle then you are fine. If you do want to have the proper cover installed, you can purchase one at your local dealer. Consider hiring an experienced technician like one from YourMechanic who can pick up the parts and take care of the service for you.