Moreso, 25L (just above a quarter of my tank) is not enough to let the car calibrate its closed loop. Usually it requires a full tank and lots of driving, about 800km each test. It's hard to do a consistent driving cycle for that distance.
My aggregated data shows that the circuit DECREASES mileage now, perhaps with about 10%. And that is with settings almost identical to the ones used by RaceChip, a bit more aggressive. In other words, with a REPORTED LOWER rail pressure and ACTUAL HIGHER rail pressure the CONSUMPTION INCREASES by ~10%.
I suspect that most of the people that report decreased consumption actually use on-board-computer data and do not perform precise measurements.
So I've changed my strategy now, The reported (fake) rail pressure was increased, so that it yields a lower actual pressure. This means that the software is now set to -20% instead of +20%, so the curve is reversed.
The on-board reported consumption is ~30% higher at idle (1.1L/h stock, 0.7L/h previous, 1.4L/h now). The car stays longer in high gears which also improves mileage. This makes sense, as the engine ECU now thinks the engine has 'more power' so it signals the automatic gearbox ECU to shift earlier up and retarded down. Or something....
Data from the start of the year:
- 29 litres, 90km since refuel, 11.6/% shown, actual 11.6-12.4/% (tuning unit was not connected)
- 72.64 litres, 935km since refuel, 7.4/% shown, actual 8.6/%
- 64.55 litres, 667km since refuel, 8.2/% shown, actual 9.6/%
The driving conditions were not identical, but the actual figures are slightly higher than stock, taking into account the driving style.
I will need at least two more months of testing to draw a definitive conclusion. But the initial conclusion is that most of the aftermarket units that report a [fake] lower rail pressure do not increase mileage. Sorry to burst anyone's bubble, but I'm into that group as well.
The other conclusion is that the circuit and software can still be used as-is, no changes are required if you want to do your own testing. I do have an improved, unpublished, Android application, but it mostly increases usability. If anyone wants the apk for that just drop me a note.