Sustainable purchasing in the automotive industry is present as never before. The Supply Chain Act in Germany and the European Green Deal (EGD) are legal incentives to focus on sustainability across industries. The automotive industry is large and important in Europe, which implements new purchasing channels through the supply chains. Suppliers are usually Small and medium-sized enterprises (SMEs), which account for 99% of the European economy (Europäische Kommission, 2003). Original Equipment Manufacturers (OEMs) have already passed on their climate neutrality targets to suppliers and called for worldwide engagement throughout the supply chain. In addition to the necessary emission reductions in the individual parts of the value chain, there are growing demands for a product footprint to show the CO2 emissions for the supplied parts. The CO2 emissions should be systematically reduced. This study shows how transparency in purchasing can be created and how this transparency can be used to impact sustainable purchasing. This study continues different studies chronologically from 2016 until March 2022. The results are confirmed by ten expert interviews with specialists in the automotive industry. The focus is on digitisation in purchasing and is linked to the resulting transparency. Transparency shows how the impact on sustainable purchasing can be increased by using cost brake downs (CBD) and provides an outlook on CO2 CBD (Product Carbon Footprint) to reduce CO2 emissions.