Current automotive designs lack security solutions that span the vehicle lifetime. Future Service-Oriented Architectures (SOAs) in cars will enable post-sale updates and functional upgrades, which require prevalent proof of authenticity for the service suppliers as well as the manufacturer (OEM). In this poster, we decouple the cryptographic authentication of the service suppliers from that of OEMs with the help of DNSSEC. We propose to authenticate in-vehicle services by certificates that are solely generated by the service suppliers but published via DNSSEC TLSA records solely signed by the OEM. Building on the well-established Internet standard DNSSEC ensures updatability and interoperability with various protocols. Our approach enables credential management for millions of connected vehicles with proven security.