In 2006, fluid filters (e.g., fluid power, municipal water and waste, consumer water and industrial fluid filters) accounted for the largest share of total shipments, with 38 percent of the overall market, according to Freedonia. Growth in this segment going forward will be buoyed by strong gains in the consumer market and interest in input reclamation processes and water recycling. Although they compete with high-end membrane separation technologies, fluid filters will are also expected to benefit from their use as pre-treatment steps for these technologies. Shipments of air filters are expected to post the strongest growth through 2011, driven primarily by changes in environmental regulations and gains in the consumer market. The internal combustion engine and related filter segment (e.g., oil, air intake, fuel, and cabin air) is a relatively mature product group that is expected to post more modest gains, but will benefit from the ongoing development of new types of diesel engine filters and a growing aftermarket for cabin air filters, according to Freedonia. The motor vehicle market will continue to account for the largest portion of total demand, with a 24 percent share in 2011, despite below average growth. The high volume of these oil, fuel, and air-intake filters sold as original equipment and in the aftermarket more than offsets their relatively low unit prices, according to Freedonia. Demand for filters in the other transportation equipment and utilities markets is projected to post the strongest gains, powered by current and pending regulations and concerns about the quality of air and potable water supplies. Demand for filters used in diesel-powered, off-road equipment are also expected to post strong gains, primarily stemming from pending regulatory changes.