This paper deals with a coupled longitudinal/lateral vehicle nonlinear control and road bank angle estimation. The control law is designed using the differential flatness property of nonlinear longitudinal and lateral vehicle model. An algebraic estimation approach is employed to estimate simultaneously the vehicle dynamic parameters (like lateral forces and roll angle) and unknown inputs (like road bank angle and corrective yaw moment). The control and estimation approaches use also the algebraic estimators to perform the filtering and the numerical derivatives of noisy measurements. To perform some coupled vehicle tasks like an automatic line keeping of straight or curved lines, a line change maneuver, obstacle avoidance, a combined control of longitudinal and lateral vehicle motions is required. Note that this controller is designed via steering angle and traction/braking torque of vehicle. Furthermore, some other parameters like road bank angle has an important influence on vehicle lateral dynamics behavior and control vehicle systems. For this, the algebraic based unknown input estimator is considered here to estimate road bank angle and consider a more realistic trajectories. Interesting results are obtained using real data which are acquired under high lateral accelerations.