Engineering of complex systems often involves teamwork. The members of an engineering team must work together to identify design requirements, explore design spaces, generate design alternatives, and make both interactive and joint design decisions. Because of the latency of information and the disciplinary differences, it is often a difficult process for the members of a team to reach agreements when needed. Negotiation has been studied as a method for facilitating information exchange, mutual understanding, and joint decision making. An argumentation-based negotiation approach was previously proposed by the authors to support collaborative engineering design. In this paper, we present an experiment study that was conducted to evaluate the impact of this negotiation support approach on the process and the outcome of collaborative design. The results of the experiment show both positive effects and limitations of the approach.