Intelligent Transport Systems (ITS) have the potential to increase road-network capacities, reduce congestion and pollution, create shorter and more predictable journey times and significantly improve road-user safety. However, these technologies will also have the ability to track a citizen’s every move, extracting information about their daily lives. It has been argued that privacy invasions caused by ITS will have a damaging effect on society, creating a ‘Big Brother’ or panopticon state. For these fears to be fulfilled, it needs to be the case that citizens are not only concerned about the privacy impacts of ITS, but that the ITS will actually cause citizens to change their travel behaviour. This paper explores the privacy decisionmaking process individuals will use to determine whether the implementation of future ITS will cause them to change their travel behaviour. The results of a Europe-wide survey have shown that when faced with a decision about whether to disclose personal information or not, future ITS users will be more influenced by irrational factors than rational ones. In addition, users will be more influenced by their perceptions of the risks associated with disclosing personal information (data sensitivity, trust in the data holder and trust in the transfer method) than the reward on offer.