This paper presents dynamic models associated to an experimental Diesel engine platform. Stability, controllability and observability analysis of the models have been performed. While the impact on human's health of NOx emissions is addressed, a state-feedback control procedure is presented in order to control the air flow inside the intake manifold to the cylinders and the pressure inside the combustion chamber of the experimental Diesel engine. The proposed solution of optimal control of the combustion regime brings important improvements of the Diesel engine: NOx reduction and fuel saving.