FL 740d und 750d Verbrauch

[HatTrick]

Hello everyone!

My first post here. Excuse me for writing in english but my german is not quite good enough to discuss cars on a forum.

I'm currently driving an E65-740d 2004 when commuting to work which is a 200km round trip and about 50tkm/year. So far I've done about 190tkm in this car over the 4 years that I've owned it.
My average consumtion is 8.5L/100km (specified combined is 9.7) and I get about 1050km on one full tank. Speed varies between 50-130km/h with an average of around 70km/h.

I have begun doing research for my next car that will be replacing this 740d in about 3 years time. I don't really like the interior styling of MB or Audi so most likely I'll be staying with BMW.
There's three models I'm looking at since I want to spend my commute in comfort and with power but also low consumption, 640d (just love that body), 740d and 750d.

I have driven the FL F01-730d but I just find it too tired and weak compared to my E65 so that's not an option.
Last week I got the chance to spend an hour with a 750Ld,  BMW 750Ld Test drive , and pretty much fell in love with it.
The comfort seats eventhough they look the same as the E65 was a tad more comfortable. The ride on highways was quiet and very comfortable just as it should. When stepping on the gas pedal it does give off that typical 6-cyl roar quite different from the V8 diesel but not annoying and the power was really brutal. Didn't really notice much of the turbo lag.

I have not had the chance to try the 640d or FL 740d yet as the dealers around here are very stingy when it comes to testdriving these models but I'm working on it.

The one thing I could not estimate from my time with the 750Ld was what kind of average consumption I can expect on the roads that I commute.
I've read the comments here in several threads that people find the 750d thirsty for a diesel but also that the same people seems to drive quite fast 130-220km/h or a high degree of city driving which of course would lead to a higher consumption.
In my own driving I have max 5% city and the rest is mostly cruising along smaller countryside roads with very few stops.

So I'm asking if anyone here is driving a 640d, FL 740d or 750d over longer distances with modest speeds and what kind of consumption you're getting?

Another reason I would find the 750d more attractive over a 740d is when looking at cars on mobile.de there are much more 750d's with a very high number of options compared to 740d's.

After living with a very well equipped E65,  BMW vin decoder online, I don't want to step down in this regard plus now there are even more fun options to be had.