The oil pump can easily consume a few HP at higher rpms so a lower restriction oil filter can marginally contribute to better mpg.

I am using an over sized Mobil 1 M1-209 oil filter. It's the same diameter as the standard OEM filter but at least one inch longer for many more square inches of filter media and thus lower back pressure and pumping restriction.

All the filter sizes are typically the same price from a manufacturer so the extra capacity comes free. The drain back valve, bypass valve, and gasket size are all the same specs as the OEM filter.