[Doggie 1]

I can't recall exactly what mine shows, but it's seven hundred and something every time.
It re-adjusts itself the closer the end of the tank is.

[Dazzler]

First time i filled up the tank,computer displayed 800 km to empty.That figure was showed only once.Since then every time i fill it up it shows 730km.
Any ideas?

My Hybrid does this .. It looks at your overall average since last reset and then tries to work out the distance to empty estimate. The Lower the average fuel use figure, the higher the distance to empty..

Therefore I'm guessing your average fuel use figure went up between fills.