[mechman600]

The leg home was actually a 30% fuel savings (5.2L/100km vs the normal 7.4L/100km) and this was changing only the highway portion of the leg (47% of the leg's distance). For me that is pretty conclusive - more than the [likely] result of simply lowering my speed.

My normal 60 km/h cruising speed is around 5.5-6.0L/100km, not that I have ever really tested it properly. Maybe I should. Add that to the list.

I know this isn't scientific testing, but I rarely drive this car because it's my wife's. Scientific testing would require burning more fuel than I normally would, and I would rather save the money!