My Dci QQ fuel computer reads 7% optimistic
My Dci Juke reads 3% optimistic
Both cars are under 6 months old and are the same engine spec,6 gear 1500 Dci units
True fuel consumption is better in the QQ on varied town and short journy driving
The Jukes fuel consumption is shocking when the engine and conditions are very cold, 30 mile trip from -3deg delivered aprox 39mpg on the computer
They very same trip back home with a hot engine and +4deg returned 55mpg on the computer,.
On the outward trip with the cold engine the fuel computer would not rise above 30mpg for the first 5-10 miles, the severe cold knocks the economy very badly