Consumer push for greater sustainability continues to have an influence on automakers. Among other areas, this is translating into continued research into the use of biodegradable materials--those that can be absorbed into the environment harmlessly--for everything from foam to plastic in an effort to build an automobile that is a bit more green, even after its useful life is over. For example, Ford and other car makers have begun incorporating wheat straw, soy products, and other natural materials into car parts. These first steps have the ultimate goal of creating cars with completely biodegradable interiors. Straw and soy aren't the only materials being studied and put into use. Other plant-based substances are likely to come into play. Some day, you may be adjusting a headrest made of coconut husks or a glove box made of carrots.