I have my 2015 S Leaf for 15 months, and 16K miles in NY, which is hot and cold. I from my scientific experiments, I can tell you :
1) With L1 (120 volt) charging, if you are plugged into the charger, you CANNOT do any preheating, as the car will not engage the heating elements at all, it will only blow air and use up your battery.
2) With L2 (240 Volt) charging, the car will warm up with the car plugged in, BUT your % of charge will either stay the same, or go down, even though the car was in charging mode!.
3) In cold weather (20-32 degrees), the car will give you about a 60 mile range (starting from 100% and stopping to recharge at 20%), soo... In effect driving 60 miles will cost you 20% of y our total charge to heat your car. WITH THE FOLLOWING CONDITIONS - Speed - 55 mph or lower, Heat set to 68 degrees, with the fan at 2 bars, no a/c running, and relatively flat terrain (I am in Long Island).
4) I can imagine that with 0-20 degrees cold, faster speed, higher heat temperature and fan, a/c on, stop and go traffic, and hilly, mountain terrain, your range (from 100%) is possible to only be 30-40 miles range in the winter.
Although I love my car, and it works GREAT for me, I have the following CAUTIONS for potential new Leaf drivers...
Others please comment----
The Leaf IS NOT A CAR FOR PEOPLE WHO LIVE IN COLD CLIMATES, MOUNTAINOUS AREAS, WHO NEED TO TRAVEL AT (OVER 55 MPH) HIGHWAY SPEEDS, LOVE HEAT AND AIR CONDITIONING, AND THEN EXPECT TO TRAVEL MORE THAN 20-35 MILES AT A TIME!!!