This Small Business Innovation Research Phase I project plans to demonstrate that compression-ignition (diesel) engines are an attractive candidate technology for light duty vehicles due to their much higher baseline thermal efficiency than spark-ignited, throttled gasoline fueled engines. Diesel engines are used extensively in Class 3 to Class 8 vehicles but will require significant reductions in emissions of oxides of nitrogen (NOx) and particulate matter before current and anticipated light duty emissions standards may be met. The use of present day heavy duty diesel engine technology in a mid-size vehicle would imply NOx emissions of 0.8-1.0 grams per mile (g/mi.), well above Tier I standards of 0.4 g/mi. or ULEV standards of 0.2 g/mi. Furthermore, the lack of real-time sensor technology to characterize NOx emissions prevents the application of recent innovations in control, which may address the nonlinear, varying nature of Cl engine dynamics. In Phase I, NeuroDyne and Ion Optics propose to apply innovative IR `smart` sensing technology to identify and characterize NOx emissions using a Navistar V-8 diesel engine. This combination will yield a small, low power, thermally stable and cost effective IR emissions sensor applicable to diesel or spark-ignition engines. This effort will provide the necessary feedback information to enable the development of reduced emissions control in next generation vehicles. Eaton Corporation has reviewed our design and has offered to beta-test the sensor for potential inclusion in their automotive and truck equipment product line.