Engine performance data
Engine performance data are sent automatically through ACARS.
Now, IF such data were actually downlinked by the aircraft and indicate an additional 4 hour flight time, then two questions arise:
1) Where did the WSJ take this information from? Boeing? ARINC?
2) Why did Malaysia Airlines declared at an earlier stage of the investigation that no ACARS had been received after the time the aircraft had disappeared?
Either someone is speculating without any shred of evidence or someone is withholding vital information for some reason.