That's assuming you used all 70L worth of tank space. If you had a 1/4 left, then the maths is off, and the savings (as you suggested) are greater. Notwithstanding, I drive a fleet worth of Camry's, and I have never seen or heard of such good mileage. 700km, perhaps, if your name is Daisy. Not bad, keep it up and the environment will love you!