Recent advances in technology leads to increasing high speed performance of submicrometer electron devices by the scaling of both process and geometry. In order to aid the design of these devices it is necessary to utilize powerful numerical simulation tools. In an industrial environment the simulation codes based on the Drift-Diffusion models have been widely used. However the shrinking dimension of the devices causes the Drift-Diffusion based simulators to become less accurate. Then it is necessary to utilize more refined models (including higher order moments of the distribution function) in order to correctly predict the behaviour of these devices. Several hydrodynamical models have been considered as viable simulation tools. It is possible to discriminate among the several hydrodynamical models on the basis of their results on the output characteristics of the electron device which are measurable (I-V curves). We have analyzed two classes of hydrodynamical models: i) HFIELDS hydrodynamical models and HFIELDS drift-diffusion model; ii) self-consistent extended hydrodynamical models with relaxation times determined from Monte Carlo simulations.