The growing relevance of vehicular applications like media player, navigation system, or speedometer using graphical presentation has lead to an increasing number of displays in modern cars. This effectuates the desire for flexible sharing of all the available displays between several applications. However, automotive requirements include many regulations to avoid driver distraction to ensure safety. To allow for safe sharing of the available screen surface between the many safety-critical and non-safety-critical applications, adequate access control systems are required. We use the notion of \emph{contexts} to dynamically determine, which application is allowed to access which display area. A context can be derived from vehicle sensors (e.g., the current speed), or be an application-specific state (e.g., which menu item is selected). We propose an access control model that is inherently aware of the context of the car and the applications. It provides delegation of access rights to display areas by applications. We implemented a proof-of-concept implementation that demonstrates the feasibility of our concept and evaluated the latency introduced by access control. Our results show that the delay reacting on dynamic context changes is small enough for automotive scenarios.