CLEVELAND — According to a new study, entitled “Diesel Engines,” from The Freedonia Group, Inc., U.S. demand for diesel engines and related aftermarket parts is forecast to increase 4.2 percent annually through 2009 to $16.3 billion. This is a substantial increase over the performance registered during the 1999-2004 period, when key diesel engine markets, such as heavy-duty trucks, experienced sharp production declines. Gains will be driven in general by continued expansion of the U.S. economy. Although motor vehicle diesel engines will still comprise the largest product segment in 2009, off-highway diesel engines will grow faster, spurred by renewed growth in such large markets as construction and agricultural equipment, both of which have a high degree of diesel engine penetration. The fastest-growing off-highway markets will be marine equipment and electric power generation, supported by heightened boat building and shipbuilding activity, as well as by rising interest in off-grid electric power sources precipitated, in part, by the major blackout experienced in the Northeast United States in August 2003. Heavy-duty trucks will remain the largest motor vehicle market for diesel engines, despite pro-jected declines in heavy-duty truck production through 2009. Light-duty trucks will continue to be the second-largest motor vehicle market and experience the most rapid growth, with the other motor vehicle market — which includes specialty vehicles — posting the second-largest gains. Additionally, technological innovations, many of which will be prompted by federally mandated emissions control regulations, will spur demand for new, cleaner-burning diesel engines and components at both the original equipment manufacturing and aftermarket levels in the motor vehicle and off-highway segments.