Sure you can get high millage with newer cars, my 1998 Suzuki Swift did 50 mpg on the highway. Also, that is actual calculation and not the false thing the display tells you Regarding the update, people you keep disappointing yourself and others with the random estimated release dates. All we know is that the update will probably be released soon. I am personally unsure about the bluebuck as the video released only showed the windshield and not the full interior, so I have a feeling there might be some work left. Hopefully it will be finished before the next update release.
Meanwhile I'm getting like 10-15L/100km in a 75hp I4 shitbox which weights only about 100kg... not everything evolves around fuel consumption guys. Sometimes you can just have fun. Now please go back on topic, alright? I have a feeling we might get a Bolide rework some time soon, since its the only car in game which really shows its age with basically next to no improvements since it was released.
People shall not believe onboard computers, or at least take computer-generated data with a grain of salt. Their algorithms are very rough and calculations are rarely accurate.