Key Points
- The Kia e-Niro tops a Swedish study of 9,954 EV battery tests at 97.25 percent health after 100,000km.
- All 20 top-ranked models kept over 91 percent capacity, and 19 are sold or were sold in Australia.
- Battery chemistry can shift health outcomes by more than five percentage points within the same model.
A new study out of Sweden has put a number on something EV buyers worry about but rarely see measured: how much battery capacity a car actually loses over high mileage.
Carla, a Swedish used-EV marketplace, analysed 9,954 battery tests carried out on EVs between 2022 and 2026, using diagnostic equipment from Austrian company AVILOO. Of the 20 models ranked, 19 are available or have previously been sold in Australia, making the results directly relevant to the local used-EV market.
The top 20 models by battery health after 100,000km
The Kia e-Niro (64kWh) topped the list at 97.25 percent battery health, just ahead of the Hyundai Kona (64kWh) at 97.18 percent. Every model in the top 20 retained more than 91 percent of its original capacity.
Carla's data was collected only from models with a large enough sample size to be statistically meaningful, so lower-volume or newer models are not represented.
Battery chemistry matters even within the same model
The study also found that a single model can show very different battery health results depending on the chemistry and supplier of its battery pack. The clearest example is the Tesla Model 3, which has used four different battery configurations across its production run in Sweden. The Model 3 variants using LFP battery packs experienced the lowest battery degradation.
Tesla Model 3 battery health by pack chemistry
Battery | Battery Health After 100,000km (%) |
CATL LFP | 93.3 |
LG Chem | 91.5 |
Panasonic 77.8 | 89.8 |
Panasonic 52.4 | 88.2 |
The gap between the best and worst-performing Model 3 battery variant is more than five percentage points, larger than the gap between many different car models entirely. Carla's researchers say this shows battery chemistry can matter as much as the car model itself when it comes to long-term durability.
What this means for used EV buyers
For anyone shopping for a used EV, the overall picture is reassuring. Most of the models that dominate the used market in Sweden are still showing strong battery health well past 100,000km, at levels higher than many buyers assume.
That said, the study confirms there are real differences between models and even between versions of the same model. Carla's researchers suggest a battery test remains a useful check alongside the usual factors like year, mileage, and equipment level when comparing used EVs.
On average, the range lost to battery degradation across these 20 models works out to around 32km, a gap that would have little to no impact on everyday driving.
About the study
The analysis is based on 9,954 battery tests carried out in Sweden between 2022 and 2026, using AVILOO's battery diagnostic tools, covering a broad range of EVs from the Swedish used-car market. Carla says this is part of a wider 2026 EV battery study, with further analyses planned on battery health by brand and how commonly batteries show heavy degradation.
About the author
Danny is a consultant and entrepreneur working at the cutting edge of the electric vehicle and energy transition. He is passionate about educating and helping consumers make better decisions through data.
