New job - my commute is 91km one way (fortunately, my dad's place is only 8km away
). I estimate 35,000km driven annually now. Average in the Mazda 3 (measured by hand since I don't have a computer readout) is typically 7.6L/100km in pure highway driving. Imagine shaving 3L/100km off that...
1,050L of fuel saved each year, which at the current ~$1.299 = $1,363.95 saved per year.
I'm not trading up since my Mazda has 29,300km at the moment, but if I were looking to upgrade, Mazda's unlimited mileage warranty would be a huge factor to me, as would fuel economy afforded by a Prius, Volt, or Corolla LE Eco.