New telematics data from fleet management platform Geotab reveals that vehicle speed exerts a significantly greater impact on electric vehicle (EV) range reduction during summer months than high ambient temperatures. This finding, derived from an analysis of 350,000 trips from 500 sedans and 2.8 million trips from 2,000 light cargo vans, challenges common assumptions about EV performance in hot weather and provides critical insights for fleet operators and EV owners aiming to optimize energy efficiency.

While high ambient temperatures do affect an EV’s range, particularly at lower speeds where energy consumption for cabin and battery cooling becomes more apparent, Geotab’s data indicates this effect diminishes as vehicle velocity increases. Charlotte Argue, senior manager of sustainability at Geotab, noted, “At low speeds, a 10-degree change in temperature will have a much larger impact on range than any change in temperature at high speeds.” This suggests that while air conditioning usage in heatwaves draws power, its proportional impact on overall range is less at higher speeds.

Conversely, speed emerges as the predominant factor in range degradation due to increased wind resistance. Geotab’s analysis demonstrates a steep decline in range with even modest speed increases. For instance, a 65 kWh electric van traveling at 50 mph in 86°F heat with air conditioning on typically achieves a range of approximately 143 miles. Elevating that speed to 60 mph reduces the range to 121 miles, a drop to 103 miles at 70 mph, and further to just 88 miles at 80 mph. This represents a substantial 39% reduction in range between 50 mph and 80 mph, underscoring the critical role of aerodynamics at higher velocities.

“Drivers tend to worry about using the air conditioner in hot weather, but our data shows that your right foot can make the biggest difference, particularly at high speeds,” Argue stated. She emphasized that reducing speed by as little as 10 to 15 mph can extend range by 20% to 30%, depending on the vehicle model. These findings align with broader automotive research indicating a strong correlation between speed and the energy required to overcome drag.

To maximize EV range in summer conditions, Geotab recommends several practical strategies. Drivers should prioritize reducing speeds, as even small adjustments yield significant benefits. Pre-cooling the cabin while the vehicle is still plugged into a charger utilizes grid power instead of the battery. Efficient use of air conditioning, such as employing the recirculation system or opting for seat ventilation, can also conserve energy. Furthermore, avoiding aggressive acceleration and practicing gradual braking enhances regenerative braking efficiency, and parking in shaded areas helps mitigate heat buildup. Finally, opting for slower charging methods when temperatures are already high can reduce heat generation within the battery pack, potentially contributing to long-term battery health.