Battery degradation is one of the main concerns when buying an electric car, especially when looking at a used EV. Mileage is important, but by itself it does not tell enough about how old the battery really is.
Two electric cars with similar mileage can have very different battery health, depending on driving style, climate, charging habits and the model itself. That is why the analysis of the Swedish platform Carla, which deals with the sale of used cars, is interesting. The company conducted nearly 10,000 EV battery health tests conducted between 2022 and 2026 to determine which models best retain capacity after 100,000 kilometers.
The results show that several popular electric cars still maintain battery capacity of 95 percent or more, but Korean models stand out at the top.
The best result was achieved by the Kia e-Niro, known in the US as the Niro Electric. Its 64 kWh battery retained an average of 97.25 percent of its initial capacity. Right behind it is the technically related Hyundai Kona Electric with 97.18 percent. This means less than three percent degradation after about 100,000 kilometers, which is an extremely good result.
The Kia e-Niro and Hyundai Kona Electric retained more than 97% of battery capacity
The third place was taken by the Kia EV6, with a battery of 77.4 kWh and an average health of 95.95 percent. They are followed by the Volvo XC40 Recharge, whose battery with CATL cells retains 94.70 percent of its capacity, and the Polestar 2 with cells from the same supplier, which achieved 94.35 percent. The BMW i3 with a larger 42.2 kWh battery, introduced in 2019, finished sixth with 93.77 percent.
CarlaInterestingly, the Kia e-Niro and Hyundai Kona Electric are older models, although one would expect the newer electric cars to have an advantage due to advances in battery technology. One possible explanation is that these two Korean models put less strain on the battery. Their liquid-cooled packs charge at less than 80 kW, which is well below the capabilities of many newer EV models. Slower charging reduces the heat and electrical load on the cells, and it is heat and high current that are associated with faster aging of the battery.
On the other hand, the Kia EV6 shows that fast charging does not automatically mean a bad result. This 800-volt model charges about three times faster than the e-Niro and Kona Electric models, but still retains a very high percentage of capacity. Sweden’s cooler climate could have helped, although the same condition applied to all the cars tested.
Another detail should be kept in mind with the Hyundai Kona Electric model. Hyundai previously replaced the entire battery packs on a number of early Kona EVs due to problems with LG Energy Solution cells linked to fire risks. It is not clear if the models with replaced batteries were excluded from the analysis, so this could partially improve the Kona model average. The Kia e-Niro used cells from another supplier and was not part of that recall.
However, the bigger picture is positive. Among the 20 best-ranked models, the degradation was less than 10 percent. Even the Volkswagen ID.3, which finished last in this group, retained an average of 91.79 percent of battery capacity after 100,000 kilometers.
This analysis confirms what more and more research is showing: degradation of EV batteries does exist, but it is mostly gradual and not the dramatic drop in capacity that many fear. Modern electric cars can retain a large majority of their original capacity even after serious mileage, which is especially important information for buyers of used EV models, reports InsideEVs.