2009 Jazz – contradiction between consumption and display

Hello, our Jazz have driven now 2000 kilometers. Are in total very satisfied, two things are negatively noticeable: 1. The disks fog unceasingly fast. Not only behind, but in the whole vehicle. Only the air conditioning helps here. Of course is quite unsightly, as this affects the fuel consumption. The stated consumption can be observed only in the city in approximately. On the highway the consumption with us was 120-140 km/h at 6,3-6.5 liters. However, is ok, if 2. What’s really stupid is the inconsistency between the tank display and the kilometers driven. We had 420 kilometers after full fuelling the tank display was zero (motorway ride) and the message was that we would now drive on reserve. This is almost 8 liters. The on-board computer indicated at this time that the range was still 40 kilometers. At 440 kilometers I fueled, but it was suitable for With a consumption of 6.5 liters after 440 kilometers, actually about 28 liters are consumed, but why do I get the message that the tank is empty so quickly with a tank that holds 42 liters? I have experienced this in total 3 times. Actually I would have to be able to drive a good 200 kilometers (with a consumption of 6.5 liters)!! If anyone has an explanation for this, the display is also so inaccurate with other jazz owners and therefore in the Gru and unnecessary? Greetings Peter