The only way to check fuel consumption is over a long period of time. Writing down liters added and speedo mileage. It will be a true overall average. I don't know if the instrument average is accurate or not...if it is then fine. If you want the average for a single run, then you have to fill up at the same pump, pointing the same way. A sloping concrete pad in front of the pump can change the fill up volume by several liters easily. This aspect will all even out over many km. and many fill-ups at different pumps. For a single fill, wind strength and direction can also make a huge difference. For a single fill, it could be windy on the way out and calm coming back. Making the numbers incorrect even if other aspects are equal.
I think that we have entered a new era of short higher cars Spark, Micra, Trax and Buick equiv; that may make sporty low (if you will) seem old. They are not SUVs, just small convenient vehicles for many.