Thermal Engine Encapsulation (TEE) is a technique for reducing heat loss from an engine after it has been switched off, in order to get a warmer re-start. This practice yields benefits in terms of fuel economy, emissions and wear, especially for vehicles used for short journeys in cold weathers and with engines warming up slowly.In this study, the encapsulation of a small automotive Diesel engine is investigated by means of theoretical and experimental analyses. In particular, the influence of oil temperature on brake specific fuel consumption and emissions is calculated. Furthermore, the thermal behavior of the engine has been simulated by a lumped-capacitance model, in order to assess the correlation between encapsulation thickness and cool-down time.Finally, the 0-D thermal model and the 1-D engine model have been coupled in order to predict the influence of engine cranking temperature on fuel consumption and pollutant emissions, considering a B-class vehicle running a short journey (15 minutes) at medium speed and load and very low external temperature (0°C).