Driver assistance systems need more and more precise information about the vehicle driving situation. While a certain number of sensors is available, some important variables are not measurable. A sensor platform is designed, which consists of a sensor fault detection and diagnosis system, the design of a fault tolerant sensor system and the estimation of non-measurable variables. The features are generated by parity equations, parameter estimation and fault observers and are reduced to a suitable set. After locating the defective sensor the faulty sensor signal is substituted by a calculated one using an Extended Kalman Filter and a two-track model. Additionally, the roll angle is estimated and the road surface is classified to provide these information to the control systems.