Increasing demand for a comfortable cabin environment makes it necessary, as early as the construction phase, to estimate what effect different factors will have on the driver and passenger. Full-scale measurements and numerical simulations have been carried out in order to investigate how well computational fluid dynamics (CFD) and thermal manikins are able to predict the perceived thermal climate. The heat loss from real or virtual manikins interacts with the environment around the body, as well as thermal interaction with windows; ventilation and seat are influencing the manikins. When manikin heat loss is linked to human thermal sensations in new comfort zone diagrams, the local as well as total thermal situation can be clearly presented. Simulations of this type will enable engineers to make better decisions and early predictions in the design and construction process, improving the thermal comfort in the vehicle environment.