Porsche announced publicly that they'd be running the 919 in a modified and unrestricted form throughout this year as a "farewell tour" to try and break some track records as well.
Well...
http://www.endurance-info.com/fr/la-...francorchamps/
...apparently the mods include a Pikes Peak-style rear wing.
But in all seriousness, the article says the car was spotted running at Spa with a near-army of engineers on hand.