3-4 km is really short in my opinion, your engine won’t warm up enough. I ride mono cylinder foremost 30 years now and in the city traffic you’ll have to shift a lot for someone coming from a scooter (without gears)
I had a duke 125: 3L/100km in the city traffic and today with the 401, I am at 4.5/5L/100 if I do only short rides in the city (15-20km/day)
Otherwise its a great “learner” bike much more comfy than the vitpilen. You’ll love it