Hypermiling in a Diesel

[8$PG]

Hello!

This is my first diesel-fueled car I've owned (BMW 320dA). With the gasoline-engines it was fairly easy to get better fuel economy than the spec. but with this modern diesel I'm having a real challenge keeping it above the advertised mileage. Mostly my driving consists of long runs on the freeway with cruise control at 115-120km/h and some city/urban driving at 50km/h and through roundabouts and some traffic lights. My girlfriend takes the car to the gym now and then, short runs. Only city driving the average consumption is at around 6-7L/100km. At freeway speed it's under 5L/100km. With this kind of driving the average is pretty much right on the advertised combined figure.

With the gasoline-engines using lots of throttle when usable or none at all have helped but with the diesel I'm not so sure. Going downhill and when idling and even at constant speed on level road the consumption is really low. When accellerating alot the consumption gets much higher.

I realize keeping the speed down would do alot but it's difficult on the freeway without causing "a scene". I'm a bit curious how the couple in the Passat tdi got 84mpg (2.7L/100km). Whan kind of driving technique is required to reach this number in a Diesel? Driving at a constant 60km/h? My personal best in this car is 4.4L/100km (which is the advertised highway mileage).

Feel free to input any thoughts.