Contemporary vehicles offer an advanced telematics platform with multiple applications available such as electronic road tolling, emergency call, breakdown call, or route planning. Given the sensitivity of collected driver and vehicle data and the potential use of this data by third party applications, security mechanisms are needed to protect services as well as data. Although security has been investigated in recent telematics studies, they do not consider potentially malicious or erroneous third party applications. This paper presents a secure multi-application platform that is designed as a modular software architecture with security features to support availability, confidentiality and integrity; a proof-of-concept prototype was developed on stateof-the-art hardware and software.