It depends what you mean by it.

1) why does it have to be 0%

2) The only real issue (and not sure how much it is) is the tires, anything else is not (metal is good for many car parts, the seats can be leather or natural fibers, dashboards can be made from other materials.....) the truth is pre-1950's cars had very little "plastic" in them. The reason it is used so much is that it is very cheap and not because they need to be made of such materials or they are better

3) don't forget that most plastics today are petrochemical based, but plastics existed long before the petrochemical industry and so some of those older plastics can resurface in importance for example look up Casein plastic that is made from milk and was big before the petroleum business made it less interesting


4) like I said before, tires are the hardest to replace because there is no going back (it is easy to use a steal body or bumper like older cars instead of plastic but a car can't be built today that uses wagon wheels made of wood and iron or tires of pure natural rubber). If someone builds a car and that is the only thing that needs oil in the car that would still probably be less then what a tank full of gas needs.

But even that is not hopeless since we have stuff like [Link: popularmechanics.com] or [Link: goodyear.com] ....