Time for an update:
According to this February 2020 report (
https://www.transportation.gov/sites...t02072020r.pdf), a proposed rule for publishing rolling resistance of tires was supposed to be published March 30, 2020. That did not happen.
Is that the result of the current "Stay ay Home" orders? Don't know, but since NHTSA has kicked the can down the road repeatedly, I suspect not.
If a new report gets published (they seem to be published irregularly!), I'll let you know what it says.