Kinda left of field I know, but I belive the FRS still does not come equiped with the JDM underbody panels? I was wondering how much of an impact they might have on economy if you were to introduce them into the equasion along with lowering the car sligtly.
Still reading through it but found this thread really entertaining and kinda related to your query on improving economy, but from the physical mod rather than driver side of the coin -
http://www.ft86club.com/forums/showt...nderbody+panel