High injection pressures are used during the re-fueling process of vehicle tanks with compressed hydrogen, and consequently high temperatures are generated in the tank, potentially jeopardizing the system safety. Computational Fluid Dynamics (CFD) tools can help in predicting the temperature rise within vehicle tanks, providing complete and detailed 3D information on flow features and temperature distribution. In this framework, CFD simulations of hydrogen fast filling at different working conditions are performed and the accuracy of the numerical models is assessed against experimental data for a type 4 tank up to 70 MPa. Sensitivity analyses on the main modeling parameters are carried out in compliance with general CFD Best Practice Guidelines.