The purpose of this paper is to estimate accurately the vehicle attitudes, i.e. the vehicle roll and pitch angles. It is assumed that a set of data obtained from a low-price six-dimensional inertial measurement unit is available. This includes the linear acceleration of the vehicle and the angular rates of all axes. In addition, the observer exploits the data from the wheel speed sensors, and the steering-wheel angle, which are already available for recent production cars. Using the above, based on the combination of the velocity kinematics and pseudointegration of the angle kinematics, a novel scheme for reference angle selection dependent on the cornering-stiffness adaptation is adopted to observe the angles. The stability of each component of the proposed observer is investigated, and a set of assessments to confirm the performance of the entire system is arranged via experiments using a real production sport utility vehicle.