The plastics that are used for automobile battery casings is

PP (polypropylene) plastics are used for automobile battery casings.
Ketchup bottles, yoghurt containers, pharmaceutical bottles, and car battery casings are all made of polypropylene (PP). 

Most thermoplastics use this material worldwide. Packing and machine parts are among the applications. 

Low-density polyethylene, or LDPE, is a flexible, pliable, and lightweight plastic. LDPE is renowned for its flexibility, toughness, and corrosion resistance at low temperatures.

 A polymer called polystyrene (PS) is created from liquid hydrocarbon styrene, which is produced commercially from petroleum. 

The third most manufactured synthetic plastic polymer in the world is polyvinyl chloride.