The "new" battery in the 2012 has 11k miles on it and is almost 2 years old. The 2015 has 11k miles on the whole car. The 2012 has LED low beam headlights; not sure, but 2015 SV may have halogen. The 2011/2012 electric motor has more torque and the electronics are programmed to give better accelerator pedal response but the 2015 has "B" mode which greatly improves regeneration without using the brake pedal. The suspension of the 2015 is slightly firmer when new and the 2012 may be needing new shocks/struts soon, depending upon previous driving conditions. If ambient temperature is below 60 F, the 2011 and 2012 models will energize the heating elements in the hot water tank when climate control is turned on to vent even at coldest cabin temperature setting. The only way to avoid excessive heater power consumption under these conditions is to modify the HVAC control circuits (see threads on this subject). The heat pump in 2013 and later SV and SL models is much more efficient for heat and defrost in moderate temperatures than the electric hot water tank in 2011 and 2012 models. The 6 kW charger is beneficial if you need to charge during the day, but the 3.3 kW charger in the 2011 and 2012 models is more than adequate for overnight charging. As noted before, I strongly recommend the 2015 to get the more efficient heat pump system since the car will be used in the Washington, DC area.