As we know, the autonomy of BEVs (battery electric vehicles) depends enormously on weather conditions. In addition to the wind or the rain which play a little on the kilometers covered on a single charge, there is above all the outside temperature. This is why Consumer Reports has launched a long-term test with 4 EVs widespread in the USA. The multi-season test was carried out by the same drivers for each car, each time on the same day for all four models, and driven in the same way (as much as possible) on the same 172-mile loop.
This should make it possible to eliminate certain hazards, even if this test does not have a reference value like an EPA or WLTP test that can be repeated at will. The vehicles tested are:
- Ford Mustang Mach-E extended range,
- Hyundai Ioniq 5,
- Tesla Model Y Long Range,
- Volkswagen ID.4 Pro S
And the observation that will surprise, make some teeth cringe, or make people react is: “We found temperatures can have impact, but Tesla stands out for coming up short of claimed range no matter the weather”. In other words, “We found that temperatures can have an effect, but Tesla stands out by being shorter than claimed range regardless of weather.”
Surprising results for Tesla
Tests show that cold temperatures reduce battery life by 25%. It’s worse if you have to make “short” trips in cold weather and it can go up to 50% loss of autonomy. There is the heating of the cabin which plays, but the batteries also suffer from the cold, even while driving with a big down jacket.
The maximum autonomy was found at 80°F or 26/27°C. Summer temperatures that are not encountered all year round in our latitudes, far from it. But, the big surprise is above all the difference between the approved autonomy (EPA here) and the real one. Of the four vehicles, three manage to achieve approved autonomy. The only one that fails is the Tesla Model Y! Rated for 326 miles (525 km), the Model Y long range reaches 274 miles (441 km) in warm temperatures.
Where Consumer Reports wonders a little more is by looking at the weight of vehicles. The lighter Model Y does not give, in their tests, the best final consumption. Obviously, and the publication points this out itself, these tests are only tests and are absolutely not certification measures. Nevertheless, it is interesting to see such discrepancies between theory and reality, depending on time and vehicles.
Perhaps EVs should have more extensive testing protocols than the “simple” EPA and WLTP. Already, introducing a variation in ambient temperature during the test would give an indication of the drop in autonomy in winter. To read the full paper from Consumer Reports, it’s here.