most fuel-efficient rpms for subaru?

[GasSavers_McGee]

thanks for all the input.
previous to my 31 mpg tank I was getting 27 mpg on a pretty regular basis

we were caravanning with my husband's family and so I was following/chasing his dad in a toyota carolla.
never staying in one place long enough to draft or anything.

Looks like I will have to get a scanguage to see what is going on.

I am trying to test the higher rpms with this tank, but it's a hard habit to break not sliding into 5th gear at 55 mph.

thanks again