As summer heat fades, many electric vehicle drivers may still wonder how high temperatures affect range. But new data from Geotab suggests that speed, not heat, is the biggest factor in draining an EV battery.
The analysis, based on more than three million trips, compared how temperature and speed affect energy use in light-duty EVs, including sedans and cargo vans. While air conditioning does draw power, aerodynamic drag at highway speeds has a much greater impact on range.
The report dive into the numbers: A 65 kWh electric van cruising at 50 mph (80 kmh) in 30°C heat with the air conditioning on can travel about 143 miles (230 km). At 60 mph (100 kmh), range drops to 121 miles (195 km). At 70 mph (113 kmh), it falls to 103 miles 166 km), and by 80 mph (130 km), the van is down to just 88 miles (142 km), a 39 per cent drop from the most efficient speed.
Electric sedans show a similar pattern, though they are slightly more aerodynamic. At 50 mph, range is about 277 miles (446 km), but at 80 mph, it falls to 200 miles (320 km), a 28 per cent decline.
The reason comes down to physics. Aerodynamic drag increases with the square of speed, meaning doubling your speed requires four times the energy to overcome wind resistance. That’s far more than an air conditioning system will ever use.
“Drivers tend to worry about using the aircon in hot weather, but our data shows that your right foot can make the biggest difference, particularly at high speeds,” said Charlotte Argue, senior manager of sustainability at Geotab. “Just slowing down by 10 or 15 mph can extend your range by 20 to 30 per cent, depending on the vehicle.”
Temperature still matters, but mostly at lower speeds where drag is minimal and the constant draw from air conditioning becomes more noticeable. At highway speeds, speed itself is the dominant factor.
“Modern EVs have increasingly large batteries, and many can comfortably handle most daily driving — including fleet routes — on a single charge,” Argue said. “But range, on EVs or ICE vehicles, will always vary with real-world conditions: temperature, topography, traffic, and yes, speed.”
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