Since the cruising RPM is not fixed gearing responses to your query are meaningless.
But what you're trying to ascertain re efficiency is evidenced both by noting that engine
rpm will stay VERY low at elevated highway speeds because of the range of the CVT
pulleys, so that running at 80mph is both quiet (except for air noise) and efficient, at
about 32mpg. At 65mph you'll see 33-34mpg (exceptional!) because of lower Cd, of
course. On a flat 50mph road even 35mpg is attainable. Remarkable for a tall, AWD
3600lb wagon that comfortably seats 5. (Disclaimer: I sell 2016-2019 OBs and Legs in
the Boston area).
In the past the rearward transmission location fought with the loud motor for acoustic
dominance. Then Subie started insulating the hoods, and finally blanketing the CVT so
that driveline noise is masked by wind and tire noises at speed. You won't even think
about high-revving annoyances like poor fuel eco or noise, as they're absent.
I still can't find a competitive 5dr wagon that I can recommend, and do NOT recommend
buying a new-design 2020+ OB until a suspension mod is available to reduce body roll
and understeer. A 2016-2019 OB with an STi 20mm rear swaybar is a FAR better and
safer handling chassis. If you must buy new the lower Legacy Sedan is better. Lowering
the new OB a half inch by dropping tire sidewall one aspect ratio offers a slight
improvement, but you can't slam it down much smaller wheel/tire diameter without the
ECM and TCM yelling at you. 225/60R17 helps greatly with the Premium, and a bit less
so with 225/55R18 on the Limiteds. But that loose chassis tuning is the real culprit....