Well I have only had my D4s about a month, I fully charged it and just started using it going here n there as I was curious of the range I would get. First few days I kept in on assist 3, then after that I started to use assist 1 more, unless there was a hill! I tried out the speed hack for about half hour too, that was good, but that really does drain the battery, so I went back to standard mode! Anyway the battery went down to 1 bar before I decided to get it back home and charge it, that was just infer 40 miles( roughly 60 km) I am well impressed though, but from now on I won’t run the battery so low before charging, that was a one off!!