How fast do you drive on the motorway? (You will be amazed how much the mileage reduces the more you go over 60ish... 70 is not too bad)
Have you more information of the type of journeys you do. Whets the typical distance you drive? It’s very difficult to get good mileage on shorter journeys no matter how well you drive.
Try not to use the brakes, (unless you are about to hit something

) Imagine every time you touch the brakes you spend some money. Its amazing how anticipating traffic and not braking increases mileage.
I get better mileage on journeys that have roundabouts junctions etc than i do on a motorway. - When you are slowing down in gear you are effectively covering distance using no fuel, whereas in neutral you do.
I do not think changing gear up to 4,000 rpm is keeping the revs low either... Id say for economical driving you should be looking at 2,000- 2,500 rpm. Try to be in a gear keeping you around the 1,800 rpm mark. And also be aware of how the engine is working, for example if you are going up a hill then you should not work it hard in a higher gear but change down so the engine is not working so hard and use a few more revs to
help.
And for those getting more mileage using cruise, in my opinion this is just due to you not driving in an economical way normally, you most likely use the throttle more than you think. , I actually find that while cruise is very good i can drive more economically if there are lots of undulations along the route as the cruise does not take advantage of downhill sections prior to uphil sections. It can be a little on/off in these circumstances. But don’t get me wrong, cruise is very good and its one of those things you never knew you needed till you get it.
There are lots of misconceptions about economical driving; it’s not just about keeping a constant speed, its anticipation. When people break records they accelerate and then coast, accelerate and then coast... if you accelerate sensibly this gives great returns.
I have done long journeys on the a1 and m1 and get better mpg on the a1 every time even if I cover the same distance in the same time as the a1 has lots of roundabouts.