Toyota Boshoku Corp and Toyota Central R&D Labs Inc co-developed a bioplastic whose impact resistance is about 10 times higher than that of polypropylene (PP) used for auto interiors and announced it at JSAE Annual Congress (Spring). According to the two companies, the improvement in impact resistance might drastically expand the use of bioplastic. In regard to auto interior parts, it is possible to use the new bioplastic not only for door trims and other parts for which currently PP is used but also for the base materials of instrument panels, impact energy absorbers and other parts that need high impact resistance and rigidity to protect passengers at the time of impact. Furthermore, the new bioplastic is expected to be employed for auto exterior parts such as bumper modules and resin fenders. Source If we assume the "current bioplastic" is what's in the current gen3 Prius, no wonder they are easily scratched. The new version is harder than ABS plastic! I am speculating it will be used in Gen4 Prius.
The Charpy impact test has little to do with scratch resistance. It has to do with frangibility and fracture. Polypropylene, currently used in interiors of cars, is not particularly scratch resistant. It is, however, very impact resistant and cushions the blow by deforming rather than fracturing. Tenacity and the ability to deform without fracturing is the most important characteristics needed in passenger compartment materials. The Charpy test determines the ability of materials to deform without fracturing. Hard unforgiving materials that are scratch resistant are more likely to fracture. Glass and other ceramics, while hard and scratch resistant, are not particularly fracture resistant.
Yeah and is it high or low gloss? Oh while we're on this subject, ditch the graining of the plastic dash. Makes it hard to clean & gets dusty early.
