I'd disagree and agree. Halfway hypermiling will only get you so far, but it will get you halfway there. Halfway there can still be a fairly good increase, but you need to work on your driving technique to know what you're doing. Recently, I took my sister's car to work and back for a few days. I did nothing fancy at all (no engine off), only drove half the miles on the tank, and got 50% above combined EPA for the car. See
My sister's 95 Celica and me.