Strangely i use the standard stuff at the pump (91) and still get 450km+
Currently got BP Ultimate in the tank cos i didn't pay for it XD, the only differences i find are that vtec delivery and idling is a lot smoother with any 95 or 98, haven't really tested mileage but will let you know by the end of the week.
Then again i have an auto too and yeah, manual should always yield better mileage

Any 7th gen manual owners out there willing to enlighten us auto owners on the range you guys are getting?