• PVC is short for polyvinylchloride, which is a certain type of plastic. PVC is a versatile substance, and it can be used to make a variety of items, including hoses. If you pop up the hood on your car you're likely to find a variety of PVC hoses in your engine.
  
  

Radiator Hoses

• Radiator hoses, though they look like they're made of rubber, are in fact made of PVC and other artificial materials. These hoses carry engine coolant, which helps keep its temperature down (although the engine can still get very, very hot). These hoses will age and wither with time, but PVC is a hardy material that can take a lot of heat and a lot of material passing through it. However, conditions like oil on the outside of the hose can lead to a faster breakdown of the PVC material.
  
  

Electrical Insulation

• PVC hoses are also used to help keep electrical wires properly insulated. If you look at the boot that goes over your spark plugs and their attached wires, chances are that what looks like rubber might actually by an artificial PVC material. Plastic is a great insulator, and it can be made just as flexible as rubber--though it will endure longer and wear less if made properly.
  
  

Emission Hoses

• Emission hoses, as the name implies, are meant to handle the emissions the car generates. As such, the emissions hose is made out of PVC because the material won't degrade due to the fumes and the oil in car emissions. However, while it might be chemically resistant, an emission hose is not meant to endure internal pressures. If pressure builds up then the hose is pretty likely to rupture and split.