[MetroMPG]

That's really odd. Are you comparing driving styles/tank results from different times of year? EDIT: Just re-read your post. You did say that your attempt at efficiency was some time last year... but what season?

Depending on how far north you live, the impact of ambient temperature differences could easily dwarf the savings you'd see between those two driving styles (if the more efficient attempt was done in much colder weather than the fast driving).

If I were you, a ScanGauge would be on my ecomodding to-do list as item #1.

And... welcome to the site.