In order to reduce emissions of carbon dioxide from engines, a shift to carbon-neutral fuels is one of the promising alternatives. Hydrotreated vegetable oils (HVOs) are very high-quality bio-based diesel fuels, which do not have negative effects on engines, exhaust aftertreatment devices, or exhaust emissions. A research activity has been started at the Energy Department of Politecnico di Torino to investigate effects of using HVO instead of a conventional diesel fuel in a production engine. As a first step, a light duty commercial compression-ignition engine fueled with the conventional diesel fuel has been tested. In the present thesis, as the next step of the activity, a validation and sensitivity analysis of 3D-CFD (three-dimensional computational fluid dynamics) model is presented.