German automakers Daimler, Audi, and BMW have resigned from a group reviewing the safety of the new low-global-warming refrigerant hydrofluoroolefin-1234yf. SAE International, an automotive engineering group, organized the review last October after Daimler said tests it conducted showed the auto air-conditioning fluid, made by Honeywell and DuPont, could leak and cause a fire in a head-on collision. The SAE review group says it is disappointed in the resignations. A Daimler spokesman tells C&EN the firm resigned because it lacked confidence in the review group’s analytical methods. Although the review continues, the SAE group says it “has a high level of confidence” that the new refrigerant can be safely used. Daimler’s tests were unrealistic and ignored real-world collision scenarios, it adds.