MrMogenses, I also own a Model 3, and just like you I saw the rated range in my car instead of an estimated one, so that led me to use percentage instead of rated range. I suppose you can get Tesla's estimated range by opening the energy graph but that car has such good range why bother? I rarely get my car's rated range since most of my trips are ~80 mph.
I can't be exactly sure how many kms the estimated range Energica's go by but it really does seem like it uses very short distances (probably really close to your 5km number). I've experienced hopping on my bike with a SoC of 60% only to see the estimated range go UP from 30 miles to 40 miles after riding 10 miles just by taking it easy.