Last month a government-funded program led by the Australian Automobile Association (AAA) to determine real-world electric vehicle (EV) driving ranges revealed that some electric cars don’t travel anywhere near as far as they claim to.

    While these results aren’t overly surprising given manufacturer’s published numbers for both internal combustion powered and electric vehicles are determined by lab tests in controlled conditions that often don’t reflect real-world scenarios, in this case the range estimates may have actually been overinflated due to a detail missed by most – the temperatures these tests took place at.

    EVs suffer significant range reduction in very cold and very hot temperatures. The optimum operating temperature for a battery-powered vehicle is between 20-25 degrees Celsius. While the fuel consumption of combustion vehicles will also vary in colder or hotter weather, they don’t differ anywhere near as much as EVs.

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    When ambient temperature or the battery temperature within an EV is outside of that optimum temperature range, the vehicle needs to use its own battery power to either heat or cool the battery, which effectively reduces the available battery capacity for powering the vehicle and supplying propulsion.

    According to the report published on the AAA website, testing was conducted on two occasions on roads around Geelong in Victoria at temperatures of 25 degrees Celsius and 17 degrees Celsius. Both temperatures are within cooee of absolutely optimal test temperatures for an EV. Despite this, the BYD Atto 3 managed to record an average range reduction of 23 per cent compared to its published range claim.

    To give you an idea of how much worse it can get, the American Automobile Association (another AAA) found range reductions in EVs of up to 40 per cent during testing in freezing conditions (-6 degrees Celsius) when the heater was used, with ranges increasing as temperatures got closer to the optimum band.

    So, if we are seeing range reductions during testing at near optimum temperatures, like we did with the BYD Atto 3 and others, you can also expect range to reduce even further while driving in cold conditions.

    Melbourne, for example, has average winter morning temperatures of between 2-13 degrees Celsius. If you drive to work while it’s cold or are driving at night time in winter you’re likely to encounter significant range reduction.

    If you own an EV and understand how and why this is happening and then account for it, it’s not an issue at all. I will, for example, factor in a 40 per cent range reduction whenever I drive an EV in winter. For me it gives me peace of mind that I’ll reach my destination.

    But a salesman at the dealership will never tell you this when selling you the concept of an EV. You also won’t find these details published anywhere on the Tesla or BYD websites, for example, if you’re ordering a vehicle online.

    ‘Real-world’ EV range results like this, especially when they’re based on testing funded by taxpayers, should be published with greater detail explaining that they represent almost best-case scenarios in ideal conditions.

    Buyers should be able to make informed decisions when taxpayer dollars are spent on advertising these results, instead of being fed information that conceals the reality of driving an EV during colder months.

    MORE: EV range claims from BYD, Tesla, others scrutinised in new real-world testing

    Paul Maric

    Paul Maric is an Australian car expert based in Melbourne, Australia. Paul is a founder of CarExpert.com.au & formerly part of the CarAdvice founding team.