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I get about 800ks to a tank.
My maths isn't the greatest but that works out to be about 9.1L/100kms and that's presuming you're draining the whole 73L tank to empty. Even leaving a bare bones three litres in the tank would equate to 8.75L/100kms ...you either drive on nothing but freeways or you've turned it into a hybrid..
Pics of your trip computer?
Driving Miss Daisy..
did u have DFCO disabled ? durin decel your instant fuel should read less then 1LDon't stick a big cam and monster zorst on then...! If I let it coast downhill for 100km, I'm still using 9L/100KM