Generally speaking the variation you are seeing is between summer and winter driving. In the summer most EVs I know (including my Volt) will deliver MORE than the stated range. Of course it depends how you drive, 130km/h will drain the battery a lot faster than 110km/h. Just like a gas car...
150km real world range in *winter* is pretty much unheard of on any EV currently for sale. That will change real soon. Using the electricity to heat the air is pretty inefficient, especially if it is resistive heating (Volt) instead of an air-source heat pump (2013+ Nissan Leaf).
I've been known to try to push my EV range in winter by turning off the heat and driving the with my 12V heated socks on. Wife thinks I'm a little nuts, she's probably right