Consumption and parking aid

Tomorrow, after I was lucky enough to get a new Civic this year, I have a few questions about it to the community. My Civic has now about 1500 km down and I mostly drove quite economically (I at least get a 🙂 ). Unfortunately, my average consumption is about 7.5 to 8 l. Even after a 450 km motorway ride I did not get below 7 l. When does something change or is it not right? I also noticed that the consumption indicator when idle (e.g. rolling when the clutch is kicked) only rises to maximum, although actually no consumption is there before it falls to 0. Has anyone already seen this? My second question is about the parking aid (sensors). I have the problem at the moment that the alarms are rather useless, because the system covers the pages much too far. So if I park backwards between 2 cars, the system passes very quickly to the warning tone, although I only roll parallel between the vehicles. So I have no chance to check the distance to the back of course, because the system covers the pages too far. So if I park backwards, the system is already very nice and thanks to the G.