Drivers who are familiar with the characteristics of combustion-powered vehicles need to have a clear idea of what to expect from EVs for them to comfortably make the switch.
That’s why telematics specialist Geotab has compiled data from 3 million fleet vehicle trips and more than half a million hours of driving to analyze EV driving range in various weather conditions. The study also compared the performance of boxy delivery vans with slipperier sedans to observe the effect of aerodynamic drag due to higher speeds on the driving range.
Looking at the data, Geotab found that actual driving range is about 15 percent better than the rated range when driving at an optimal 68 degrees. On the other hand, extremely cold weather can slash the range by as much as 50 percent. This is mostly due to the energy required to keep the cabin and batteries at a comfortable temperature.
Speed also has a dramatic impact, though Geotab found that ideal speeds are too slow to be practical for highway driving. For around-town fleet drivers, however, it could be beneficial to prefer surface streets to highways for improved range.
That’s because aerodynamic drag increases proportionally to the square of the speed, so if you double the speed, the drag goes up by a factor of four.
During highway driving, it is crucial to avoid speeding to conserve range, especially for larger vehicles like boxy delivery vans. For surface street driving around town, aerodynamic drag has less effect, so temperature becomes the overriding factor, and mitigating the impact of temperature will preserve energy for driving range.
“Backed by real-world EV data, the analysis is intended to be used as a resource to help educate users on factors that impact EV range and build awareness of strategies to optimize EV deployment,” explained Charlotte Argue, Senior Manager of Fleet Electrification at Geotab.
At 68F the sedan’s maximum range is achieved at about 19 mph. The need to shorten the length of time running heaters makes the ideal speed at 32 degrees 37 mph because the extra energy lost to aerodynamic drag is saved in a shorter time of heater use up to that speed. Faster speeds use the heaters for even less time, but the aerodynamic drag losses overwhelm the savings.
The van has more drag, so peak efficiency occurs at slower speeds than for the car. At 68 degrees, the most efficient speed is 16 mph, which is pretty similar to the sedan. But at freezing temperatures, the optimal speed is impractically slow at approximately 25 mph.
This means that even avoiding highways will not let drivers achieve the rated driving range in their EVs, and it is important that prospective EV buyers understand and plan for this reality when switching from combustion-powered vehicles.