This paper investigates the effectiveness of voluntary approaches in a comparative case study on European and Swiss climate legislation. Voluntary approaches are known to be less environmentally effective and economic efficient than other climate policy instruments but easier to implement and more acceptable for the business community. Voluntary approaches are preferred for approaching ‘new policy issues’ where more stringent policies and measures could hardly be implemented. This case study compares the voluntary accords signed by the European Automobile Manufacturers Association (ACEA) and the Association of Swiss car importers (ASIA) signed in 1998 and 2002, respectively. Whereas ACEA committed to reduce average CO2 emissions from new passenger to 140g/km, ASIA committed to reduce average fuel consumption to 6.4l/100km by 2008. Based on expert interviews with Swiss car importers and car experts, we compare the achievements of both voluntary accords and discuss reasons for failure. Non-credible threat and strategic behavior play a key role for the poor performance of both agreements.