Mobile devices such as smartphones have gained more and more attention from security researchers and malware authors, the latter frequently attacking those platforms and stealing personal information. Vehicle on-board networks, in particular infotainment systems, are increasingly connected with such mobile devices and the internet and will soon make it possible to load and install third party applications. This makes them susceptible to new attacks similar to those which plague mobile phones and personal computers. The breach of privacy is equally sensitive in the vehicular domain. Even worse, broken security is a serious threat to car safety. In this paper, we show how traditional automotive communication systems can be instrumented with taint tracking tools in a security framework that allows to dynamically monitor data flows within and between control units to achieve elevated security and privacy.