This work is carried out on behalf of the MIADAC project (Modelling Sectoral Climate Change Policies: Mitigation, Adaptation and Acceptance) of NCCR Climate and the ClimPol project (Climate Policy Making for Enhanced Technological and Institutional Innovation) funded by the Competence Centre Environment and Sustainability (CCES) of the Swiss Federal Institute of Technology. The idea of the project is to assess the acceptability of climate policy instruments and measures by the private sector, namely by private business. The core of that work is a case study dealing with the Voluntary Agreement made by the Swiss car importers with the Swiss Federal Energy Agency on the reduction of fuel consumption between 2002 and 2008. The goal of this agreement was to reach average fuel consumption of 6.4 l / 100km of newly imported cars in Switzerland by 2008 (compared to 8.4l/100km in 2000). However, average fuel consumption of newly imported cars to Switzerland was still 7.1 l / 100km in 2008 – the agreement failed. In addition to the 2002 agreement on fuel efficiency, the Swiss CO2 law and the Energy law provide a framework for further voluntary initiatives. The programme ‘EnergySwitzerland’ and the ‘Climate Cent’ on transport fuels are further voluntary measures that aim at reducing emissions from private transport (Baranzini and Thalmann, 2004). This case study assesses the motivation of Swiss car importers for signing the agreement, its economic efficiency and environmental effectiveness as well as the reasons for its failure. With face to face interviews, I want to understand the perception and position of Swiss car importers regarding climate change and climate regulation, and their claims to policy makers. For a more comprehensive assessment, the results of that qualitative bottom-up industry case study will be integrated in the economic top-down framework for climate policy instruments. In contrast to that industry case study, policy field analysis should help to understand the impact business can have as stakeholder in the political decision process. Therefore, the analysis of the documents of the consultation process on the Swiss CO2 law will give detailed information about the positions of firms regarding climate legislation, potential coalitions, and the development of their arguments over time (1994, 1997, 2005, and 2009). More precisely, I want to draw a landscape of the groups of the firms and industries opposing climate regulation and those being in favour of it because they might expect some competitive advantage for their business resulting from stricter climate regulation (Porter and van der Linde, 1995). Drawing from the political sciences literature, I want to check if there is some evidence for business conflict resulting from climate legislation as predicted by Falkner (2008). For a conclusion, this work should give insights about the position of private business on climate policy, assess its impact on the policy process and give recommendations for more effective and more comprehensive climate policy design.