Daimler have published a press release after internal safety testing showed that 1234yf refrigerant could become flammable under certain real life conditions. http://bit.ly/TRdHex
Previous testing of 1234yf at manufacturers and test laboratories showed that it was safe. Daimler have passed on these results to the EU Commission.
Daimler have also started a recall in the US for the refrigerant. Go to http://www-odi.nhtsa.dot.gov/recalls/recallsearch.cfm and type 12V478000 as the campaign number.
EU Directive 2006/40 requires new types of vehicles after 1st January 2011 and all vehicles after 1st January 2017 to be fitted with an air conditioning system that uses a refrigerant with a Global Warming Potential (GWP) less than 150. R134a is approx 1300 and 1234yf is 4.
In addition, the Commission published a letter (http://bit.ly/XaudLn) that deals with the shortage of 1234 yf.