There are systems where you can do 60 miles on a charge on relatively flat terrain when riding at 15.5 mp/h, that the limit here in Germany.
Id recomment you take at good look at what brand for battery and drive unit you want to use, there are big differences in quality, comfort, performance, riding distance, price....
The Stromer ST2 is a nice bike but personally I prefer the slightly slower Pedelecs, those quick E-Bikes just feel and ride closer to a motorbike in my opinion.