R-1234yf is the refrigerant of the future, significantly more "eco-friendly" than its predecessors and mandated by the EU as an air conditioning coolant in all new cars as of this year. Four years from now, all cars will be required to use it. There are just a couple of minor problems with the stuff:
Enter Daimler AG. The automaker created a head-on collision test with a B-Class at their Sindelfingen test track that would lead to the pressurized refrigerant being sprayed on the engine. The result in 20 out of 20 test[s] was that the refrigerant burst into flames as soon as it hit the hot engine... Another unexpected result of the R-1234yf test was the release of hydrogen flouride, a chemical far more deadly to humans than hydrogen cyanide, emitted in such amounts that it that turned the windshield white as it began to eat into the glass.
Well, that's not a problem; the new stuff is so eco-friendly that the EU says it will enforce its mandate despite the test results. It's often been noted that human life means nothing to the dedicated religionists. Case closed.