Around 46 seconds into the video, a close up of the cam covers on the race car shows four letters: TDFI. Now, that could mean two things. Turbo diesel fuel injection, or turbo direct fuel injection.
The earlier rumors for the Porsche engine centered on what configuration it would be. Some said V8, others called those people coocoobananas and said it was a flat six, and some band of heretics have said that it would be an inline four. While the engine layout hasn't been announced, what hasn't really been discussed is Porsche possibly going for diesel fuel.
Would a diesel Porsche LMP car be that much of a surprise? Not really. Le Mans has now been won by diesel cars every year since 2006. Gas cars have been given rules concessions and diesels have been given penalties to try and equal the fight in the last few years, yet they still have won. If they didn't at least consider a diesel, they'd be making a GOB Bluth level "huge mistake."
Hat tip to eagle eyes himself, Leo Parente!