Even when fully charged, most EVs can’t travel as far as petrol or diesel vehicles with a full tank of fuel. However, the average Kiwi travels a daily distance of less than 29km by car, which is easily within an EV’s range, and according to the Energy Efficiency and Conservation Authority (EECA) 90% of all journeys are less than 90km. But there are always motorists who want to get that little bit more for their money.

The efficiency and driving range of EVs and plug-in hybrid vehicles (BEVs or PHEVs) varies based on a number of factors, such as driver habits, driving conditions and cabin temperature. Depending on the distance travelled, all-electric vehicles with a low range will need to be charged more often, which can impact the battery longevity. Because the internal combustion engine on plug-in hybrid vehicles turns on quicker, fuel costs and emissions are increased.

One of the biggest draws on an EV battery in cold weather is the heater. While petrol engine cooling systems tend to generate large amounts of heat that can be harvested to warm a car’s interior, an EV must rely on an electric-powered heater to keep a driver’s teeth from chattering.  If you turn up the heater fan speed on an EV with a 200km range, you can reduce its operating range by up to 50km.

A US study concluded that variations in the weather could influence an EV range by more than 25%. Luckily in New Zealand, we don’t experience the same extremes of hot and cold weather, but it is something worth considering.

Ways to conserve power

If you have a garage, it always makes sense to use it in the winter, whatever type of car you drive. It will help the engine, battery and interior maintain a reasonable temperature.

If you have an EV though, try to make the most of the time that it’s charging. If it’s plugged in and you’re getting ready for a trip, try to plan ahead by pre-heating or cooling the cabin while it’s still connected to its power source. This will help to prolong its electric range, particularly in extreme weather.

Many EVs come with an economy mode and it’s well worth making the most of when you’re driving. When this mode is selected, other aspects of the vehicle's performance such as the acceleration rate are limited, in order to conserve energy. It can also increase the regenerative braking capacity to put more charge back into the battery, and all of this contributes towards maximising the vehicle’s range.

Another tip if you’re behind the wheel is to avoid unnecessary hard braking, and anticipate braking instead. This will allow the vehicle's regenerative braking system to recover energy from the vehicle's forward motion and store it as electricity. Hard braking will cause the vehicle to use its conventional friction brakes, which may not recover as much energy. Also observe the speed limit as it will help you to save power, as well as keeping you and those around you safe.

Under-inflated tyres can reduce economy, so it’s important to check your tyre pressure regularly and maintain the optimal pressure determined by the manufacturer.

If using accessories, make sure they’re used wisely. Heating, air conditioning and entertainment systems affect fuel economy on all vehicles, but can have a greater effect on EVs. Try using seat warmers instead of the cabin heater as this can save energy and won’t reduce your range as much.

Some accessories like roof racks can adversely affect a vehicle's aerodynamics. If it’s not needed, we’d suggest removing them and keeping them in the garage. More than half of an engine’s efforts already go to cutting through wind resistance at highway speeds, but colder air is denser, so it takes even more effort to overcome drag.