Hello Paul , i also noticed my mileage on my bike on a fully charged battery was 43 miles in eco mode. when it was 60 miles per ride. unsure at what mileage it changed
started looking through google and come across your forum post and decided to register on this forum, to post my experience
mine is also a vitus e-sommet, bought in Feb/march 2020 with a e8000 motor, my bike has done 1064 miles now, first 800mile were mainly cross country rides, to work and back , mainly in eco , trail when needed.
then used more for trail riding in woods , so up and down hills which is what its built for, and to work and back.
it was just the other day i checked my full charge mileage, and it was 43 miles, when i remember it was 60 miles, then riding to work on Thrusday, i dropped to 2 bars of battery left ( ~40% ) checked my range and it said 9 miles!!!! , my work ride its not hard going so always in eco.
first put it down to eco, trail, boost settings being high which would offset the range, so i lowered them all, thinking it would extend my range, but it was still 43 miles.
i have a Shimano Di2 SM-PCE02, which i bought back in august, just incase i ever need it, run a full test back then and everything was fine.but as what was said before, it does not check the the motor running.
i do know my battery is at 99% battery condition, i must say i have chipped/mapped my bike, but before everyone shouts at me, its done via software and not a little box connected to the motor. and being that my shimano firmware is fairly up to date, i can not change the assist speeds to 60mph or what ever i want.
but i have changed my motor from a EU spec to a US spec motor which allows the assist to go to 19-20 mph, which is still inside Shimano allowance, my speed is still correct , so my mileage is still correct, and i have also corrected circumference of my wheels with my maxxis tyres.
have you had any updates as i see there is someone else thats also having problems,
so its not just you,
Thanks for posting your problems , its been a great help
Dean