Consumption of diesel FOFO I+II on BAB

Hello, since I will soon rewind about 30tkm/year, I think to switch to a diesel. How is the use of the respective diesel at 100km/h and at 130km/h? According to the FOFOI brochure, the difference between my 1.6 and a diesel in this range would be max. 1.5L/100km. I consume at 100km/h 6.5 and at 130km/h 7.0L. Then a change would not be worthwhile, as my car is only two years old and I would have a value loss of over 5tsd EUR, which would not more to enter.