A study of battery health in 9,954 electric vehicles sold in Sweden between 2022 and 2026 challenges concerns about rapid battery degradation in modern EVs. Conducted by online car marketplace Carla, the research used AVILOO diagnostic tools to measure battery health instead of relying only on dashboard range or manufacturer software estimates. AVILOO’s Flash Test connects through a vehicle’s OBD port and applies a statistical model developed from used-car data to estimate remaining battery health.
The Kia e-Niro ranked first, retaining 97.25% of its original battery capacity after 100,000 kilometers. The Hyundai Kona, which shares the same 64 kWh battery, followed at 97.18%. A third Korean model, the Kia EV6, took the next spot, with its 77.4 kWh battery retaining 95.95% capacity. All three are part of the Hyundai-Kia group and ranked ahead of European competitors and premium brands, including Tesla.
The Tesla Model 3 ranked eighth, with its LFP 60.5 kWh CATL battery retaining 93.94% capacity after 100,000 kilometers. The same model with an NMC battery from LG Chem recorded a slightly lower 91.5%. Both results indicate strong battery health, while the Korean-made packs held an advantage in this comparison.
European Brands Hold Their Own
Among European manufacturers, the Volvo XC40 with its CATL 69 kWh battery led the group, retaining 94.70% capacity to take fourth place overall. The Polestar 2 (CATL 78 kWh) came close behind at 94.35%. The BMW i3 recorded 93.77%, while the Polestar 2 with an LG Chem battery posted 93.53%.
Other models in the top 20 included the Audi e-tron 50 and e-tron 55 (93.02% and 92.93%), Skoda Enyaq iV (92.88%), Tesla Model S (92.80%), Volkswagen ID.4 (92.77%) and Tesla Model X (92.52%).
Battery Degradation: No Longer a Dealbreaker
Every vehicle in the ranking retained more than 90% of its battery capacity after 100,000 kilometers, a distance most owners reach only after three or four years of regular driving. That points to battery longevity rarely limiting an EV’s practical lifespan for most drivers. These are model-level results, but, not guarantees for individual cars: AVILOO’s broader analysis found SoH differences of up to 13.5 percentage points between examples of the same model. Battery size and charging patterns, as well as how a car is used, can affect an individual result.
The Swedish ranking fits into a broader picture of battery durability. AVILOO’s Certified EV Battery Report analyzed more than 500,000 independent tests conducted between 2022 and 2026 across Europe, the Americas, Australia and Asia. Its database reportedly contains more than one million tests. The report compares battery State of Health (SoH) at 50,000, 100,000 and 150,000 kilometers. In a separate global model analysis, 16 of 20 EV models had median SoH of at least 90% after 150,000 kilometers. Those international results provide context, but they are not a substitute for the Sweden-specific findings and cannot be directly compared with them.
Independent fleet research adds another perspective. Geotab’s January 2026 update put average annual degradation at 2.3% across more than 22,700 vehicles and 21 models. Charging behavior affected the average: vehicles getting less than 12% of their energy from DC fast charging showed roughly 1.5% annual degradation, compared with about 2.5% for vehicles above that share. These fleet averages show broad patterns, not what will happen to a particular car. They also draw on a different sample and measurement method from AVILOO’s mileage-based results.
Battery-health testing is gaining relevance in the used-car market, where mileage or displayed range alone cannot establish a battery’s condition. Ayvens, for example, has reportedly provided an AVILOO SoH certificate with every used electric vehicle it sells. The certificate expresses estimated remaining capacity as a percentage of the vehicle’s original condition, giving buyers and dealers a consistent diagnostic measure.
The findings reflect a wider shift in the electric vehicle market as battery chemistry and management systems improve durability. New models continue to enter the market, including the recently launched XPeng L03, which emphasizes advanced technology and competitive pricing. As covered in our feature on XPeng’s push into Spain, the bar for battery performance is rising across the industry.
Many new electric vehicles in Europe come with battery warranties that specify a minimum capacity threshold, often around 70%, over a set period and mileage limit. Exact terms vary by manufacturer, model and market. Applying Geotab’s 2.3% annual fleet-average degradation as a simple straight-line calculation would imply about 81.6% capacity after eight years, but that estimate is not directly comparable with AVILOO’s mileage-based SoH results. The Swedish data still suggests many modern EVs retain substantially more than warranty minimums in real-world use. As battery health becomes less of a concern for buyers, attention is turning to charging infrastructure and range, with overall vehicle value also in focus.
