The AAA study reveals that when the mercury dips to 20°F (about minus 7ºC) and the HVAC system is used to heat the inside of the vehicle, the average driving range is decreased by 41 percent. This means for every 100 miles of combined urban/highway driving, the range at minus 7ºC would be reduced to 59 miles.
AAA tested five electric vehicles, all with a minimum EPA estimated driving range of 100 miles, in partnership with the Automotive Club of Southern California’s Automotive Research Center. Real-world driving conditions were simulated using a dynamometer, essentially a treadmill for cars, in a closed testing cell where ambient temperature could be closely controlled. To determine the effects on driving range, scenarios for cold and hot weather conditions – both when using HVAC and not – were compared to those of driving with an outside temperature of 75°F (about 24ºC). When colder temperatures hit, electric vehicle owners to be aware of a reduction in range and the need to charge more often to minimize the chance of being stranded by a dead battery, warns AAA.
AAA’s research also found that when outside temperatures heat up to 95°F (or 35ºC) and air-conditioning is used inside the vehicle, driving range decreases by 17 percent. Additionally, an electric vehicle with a compromised driving range will require charging more often, which increases the cost to operate the vehicle. The study instance, AAA’s study found that the use of heat when it’s 20°F outside adds almost $25 more for every 1,000 miles when compared to the cost of combined urban and highway driving at 75°F.