This paper analyses the impact of transparency regulations on fuel prices in Austria, France, and Germany to provide new insights into the effects of regulatory policies. Using publicly available data from January 2005 to December 2018, we estimate synthetic difference-in-difference models to identify the causal impact of these measures. The findings reveal significant variations across countries. In France, transparency regulations did not lead to notable price changes. In Austria, the implementation of the 2011 Price Fixing Act initially reduced prices for Super 95; however, this effect was counteracted by subsequent transparency measures, ultimately causing a price increase. In Germany, the Market Transparency Unit (MTU) effectively reduced prices for Super 95 and Diesel by two to three cents per litre, particularly in the long term.