I've seen some posts (I forget which thread) where riders have reported super high mileage on a single charge...... I'd love to hear how such high mileage is possible
The first obvious thing is - ride with the assist off!
Ok, seemingly dumb answer, however .....
I've also seen threads where people claim seemingly ridiculously high mileage as well. Often, when pressed to describe their riding style, you discover that many of them do stuff like ride for a large percentage of the time at say 18mph on a bike with a 15mph assist cutoff!
Also - using things like the Yamaha PW motor. Max power of that particular motor is around the 70rpm range. Above this, the power available falls off really rapidly due to the back EMF of the motor opposing the battery voltage. If you cycle with a cadence of around 85-90rpm or more (easily achievable for a fit cyclist), then the even in the highest assist modes, you're getting very little assistance from the motor and thus very little battery drain. (note - stuff like the Bosch CX has a much higher cadence support, so this won't be as applicable).