Consumer demand for improved fuel efficiency continues driving vehicle lightweighting efforts. Despite the increasing cost of raw materials and stiff competition from high-strength steel and aluminum, the use of plastics in automotive applications continues to grow. Polymeric content in the average North American light vehicle rose slightly in 2004 from the previous year, from 285 to 291 lbs, according to the American Plastics Council. Significant improvements in material performance have been reported, including increased strength, durability, thermal oxidative stability, and weatherability.