In this paper, high order sliding mode observers are used to estimate tires longitudinal forces, vehicle side slip angle and velocity. Longitudinal forces are identified using third order SM observers, which permit, in our case, to identify these forces with a high precision and without filtration. For the estimation of the vehicle side slip angle and velocity, a SM observer based on the hierarchical super twisting algorithm is proposed permitting to reduce the error and to increase the precision. Validations with the simulator VE-DYNA pointed out the good performance and the robustness of the proposed observers. After the validation of these observers, a braking controller based on a reduced model for the vehicle centre of gravity in the (X, Y) plane is developed. The design of this controller is based on the sliding mode techniques and it is supposed to work only in the emergency cases (and after the convergence of the observers). The performance of the closed loop system (system, Observers, Controller) is carried out by means of Matlab simulations.