They say you are what you eat, but that doesn't really apply to automobiles. Instead an important question is: Which automotive exterior panel materials offer the best balance of performance and cost? Which applications will be moving from steel to plastic in the next few years? What are the latest trends and forecasts for in-mold coatings?

A new study by BRG Townsend Inc., called Automotive Exterior Panels - 2000, probably won't make The New York Times bestseller list, but it does answer questions concerning exterior panels, from hoods and fenders to pickup truck boxes and much more. One trend the study noted was the development of thermoplastic olefin-based nanocomposites that will make them more suitable for auto body parts. In olefins, nanocomposites can reduce weight while improving stiffness, as well as improving thermal expansion, which traditionally has been a problem for plastic body panels.

Considerable effort has been put into developing in-mold coatings that are able to meet the strict OEM requirements for gloss and scratch resistance. There have been a number of recent developments helping plastics meet these strict requirements. Another focus of ongoing research is the use of carbon nanofiber materials to create conductive polymers. Conductivity is increased sufficiently by this process to allow electrostatic painting. This enables plastic exterior panels to be painted at a much lower cost than otherwise would be possible without degrading strength or surface finish.

Among the major new applications for plastics that will be covered in the study is in the construction of pickup truck boxes. The use of plastic improves durability and dent resistance while reducing maintenance costs. General Motors will be using a mica-filled polyurea for the box on the 2001 Chevy Silverado 1500 Series, while Ford will produce an SMC bed for its Explorer SportTrac.