The ACO published revisions to their 2016 rules, but of note is Article 6.9.5 of the ACO's technical regs, which take effect this weekend:
http://www.fia.com/file/34642/download?token=QUDSEC8u
This seems to be, awkward English wording aside, aimed at Porsche's fiddling with their refueling receptical and fuel tank inlet, and also seems to make what Porsche has done basically illegal from this weekend onward until the end of the 2016 season.