Advanced exhaust gas recirculation cuts nitrogen oxide (NOx) emissions in a diesel engine's cylinder without increasing the amount of particulate matter (PM) generated by significantly raising fuel injection pressures at low engine speeds (as low as 800 revolutions per minute). Higher injection pressure increases the surface area of the fuel, leading to a more efficient burn that prevents PM from forming. Multiple injection events at those low speeds and high pressure rates — as many as five in a single combustion stroke — also create a smoother combustion event that helps further retard NOx generation. Other key elements in Navistar's 2010 emissions strategy include modifying turbocharger rates, optimizing combustion with a redesigned piston bowl and careful calibration of electronic engine controls.