Gee. That sounds cool. However, polyolefins have been around for over 50 years, and they are most commonly made from petrochemicals, and used extensively in packaging. As to "bio-degradable," that is a moot point in that it can take hundreds of years for them to decompose, except in the presence of specific bacteria, or sunlight... or fire. Where does it say that the plastics in the Prius are made from cane sugar, or similar products?
I don't know if it ever specified what plant was used but in various presentations and videos The green areas are plant-based material.