Under-body shrouding and fuel economy

I hope I'm not duplicating a thread. Recently I ran over a roo and tore the front shrouding off. I noticed my economy suffered and hoped it was not because of HV battery etc. Last week I drove to Melbourne, 280-300 Kms round trip, in fine conditions and managed 4.8 L/100 Kms. Yesterday I did the same trip in near identical conditions, but with new shrouding under the front and managed 4.6L/100 Kms.

The shrouding definitely makes a difference.

It may or may not have been helped by the addition of a Laile JDM mid body stiffener. Personally I didn't expect to notice any difference with the replacement stiffener but the car was noticeably more stable.