Accuracy onboard computer ?!?

Hello everyone! I would like to add the oddities already described here with regard to the ads of the BC: My elk (2.0 D/RPF), now 2,100 km, needed at the beginning lt. BC 6,6 liters, because I was quite satisfied. When I then looked at the Km-rest display more closely, the same thing was with me, as with many of you: If display “- -“, then go still 10 liters. At the end of this display still 30 KM continued – I would have dared without the information from the forum NIE – 9,5 went still pure. Meanwhile average verb. 6,8 – more city traffic – and when I calculated after today’s refueling, however, he needed 7.5 !!! times apart from that I think this is clearly too much, but also the BC seems to spin. What do you need at all, if it is 0.8 L. vertutut? My friend meant first, he measures the last 100 km, but this is not true, it is not true since the last reset. What does your software make your new update help?