What I am finding is: Precondition, Precondition!
Yesterday I took a 103 mile trip, preconditioned in my garage which is at 45 deg F (outside temp 35 deg F) by setting the departure time,with a projected range of 88 miles when I left. I drove 103 miles starting out at 10 am and drove the 103 miles over 5 hours with 4 stops and 45 deg F on the returne home. I registered 77 miles (that included the 5 miles remaining when the Rex started) or 72 miles full EV and 30 miles with my Rex upon arriving home, slightly less than a gallon of gas, this was in ecopro+ mode driving on state routes at speeds of 50 to 60 MPH and with an elevation change starting 1000 ft above sea level up to 1250 ft back down to 800 back up to 1250 and then back down to 850 and back up again to 1230 and again back down to 800 then up to 1300 and down again to 1000 up again to 1250 and down again to 1150 for one way and then the repeat back to home.
While I admit I have only 800 miles on my i3 I am still getting good range, however in the late summer I would have been able to do the whole trip in EV in ecopro + mode and that translates as a 25% drop in range. Thank God fir the Rex at least for me, no EV charging in Walnut Creek Ohio or any other rural Ohio locations where I like to travel.
My lifetime average consumption for the i3 is 4.4 miles/kWh, which is higher then the fleet average showing on the i remote app. I usually drive in comfort mode, but I rarely use the heater and then leave it set to 60 F; however I do use the AC when it's warmer set at 73 F. I do have a year of experience driving to maximize EV in my Prius plug-in. The heater really has a big impact on range. In the summer I can get 15 miles EV in the Prius but in winter 10.8 miles is more typical.