Haha! Yup, same boat. I guess I could fill up at a half tank like you did, but since I`m doing it more as a sport than anything else, a better baseline would afford me more room to pat myself on the back- I`m sure you know how that goes!
Mine is a 94 Toyota 2WD- 4Cyl, 5 speed, standard cab with no AC or power anything, so it should be about as good as a pickup gets mileage wise. Looks like revised EPA rating of 19/25 MPG. I`ve had it for several years now, but never recorded my mileage.
PS: Don`t spend the weekend driving around the city- since you already have something of a base to go by, better to spend the weekend driving to somewhere with a lower elevation or downwind from home
