Purpose for material used for valve cover

Why is abs material used for valve cover instead of metal . What's its benefits ?

Well for one its lighter in weight, in order to gain MPH, got to make things that weigh less

other than that, I cannot figure why they would use plastic, not sure its ABS type, some kind of hi-temperature injection molded composite
like the intake manifold, Plastic
oil filter cap Plastic
bumpers plastic
head light covers plastic
even the radiator tops and bottoms are plastic too

if they can make it out of plastic they will, weight savings

Less noise. It's part of the 'emission' standards the feds shove down the manfacturer's throats.

And here you thought all those engine covers and hood blankets were to make things pretty.

It's also cheaper, no machining required.