I purchased my Kona in August and now have about 6K miles. Last week, my car had a range of 270 miles at 100% charge. Yesterday it had a 252 mile range at 100% charge. Today it had a 245 mile range at 100%. These numbers are with everything off (heater and AC). Obviously the mile range is decreasing. I assume this is not normal? is there a minimum mile range the car should have when charged at 100%? I thought at the minimum is was 258?