In this work, an observer-based sliding mode (SM) control scheme for a vehicle considering roll dynamics, is presented. The proposal considers a nonlinear higher order sliding mode reduced observer for the lateral velocity, roll angle and roll velocity. Based on this observer, the controller is designed for the reference tracking of the lateral and yaw velocities of the vehicle, using adaptive super-twisting algorithm. In order to demonstrate the stability of the closed-loop system, Lyapunov functions for each of the algorithms are used. The proposed control scheme has finite-time convergence and the robustness in presence of plant parameters variations. This is demonstrated through the performed simulation.