Nissan Micra K11 Consumption

Hello all, I got a Nissan Micra K11 (BJ 1997, 55hp, 1.0 liters) about 1 month ago and was looking forward to being able to travel regularly to the university because I had read from a consumption of 5.0 to max. 6.5 liters on 100km, which would be great. Now I am already on the road for some time and notice that I can never reach this value, because I always lie at approx. 7.5 liters. I have filled the Micra every time so far, if the tank pointer was really completely at 0, so in my opinion almost empty. However, I have never been able to fill up 30 liters until the completely full fuel. So with my 30 liters now measured 400 km, mostly highway or country road. I am always extremely slow on the road and hang for the entire 100 km route back and forth to the university behind a truck – so never drive 90 km/h. I already thought about whether it was not So far, I used the first gear only for starting up (max. 10 km/h), then slowly accelerated and switched on until I was in fifth gear at 60 km/h. Now, however, I have read from the ADAC that it is more fuel-saving to drive out gears and skip gears. So I accelerated up to 40 km/h in second gear and then switched directly to fifth gear. However, did not bring the desired result, It didn’t change anything on the 7.5 liters. I also tried to drive without radio and ventilation, so I didn’t notice any noticeable change either. I’m a little disappointed as I took the car extra because it should consume little. Meanwhile, however, I fill up almost for 100 euros a month and think it’s a bit oversized with a 1.0 liter engine. I just wanted to know if any of you can confirm these values as well or if something is wrong? Does anyone have the problem with the fuel pointer? Is this consumption still common and I’m thinking for free? Maybe you can just give your mustard to me Best regards, SamDouglas