On the 15-16 November 2012, PRESERVE and the Harmonization Task Group 1&3 jointly organized the Internation ITS Harmonization Workshop in Darmstadt, Germany. Members of HTG1&3, Standardization Organizations (IEEE, ETSI, ISO/CEN), OEM (Renault, Mitsubishi Electric, etc.), US DOT, and PRESERVE members gathered to present the results of the HTG1 (Security) and HTG3 (Communication). Discussions and panels helped drawing the conclusions and the lessons learned.