Which Electric Cars Retain Their Battery Capacity Best? Kia and Hyundai Dominate Real-World Longevity Study

A landmark Swedish study analyzing nearly 10,000 real-world EV battery diagnostics conducted between 2022 and 2026 provides definitive answers. Conducted by Carla—one of Sweden’s leading used EV platforms and a pioneer in systematic battery health certification—the research offers one of Europe's largest empirical datasets on electric vehicle battery degradation.

The standout takeaway? South Korean automakers Kia and Hyundai swept the podium, retaining unmatched battery health even after passing the 100,000 km (approx. 62,137 miles / 10,000 Swedish mil) milestone.

The Big Winners: Kia and Hyundai Lead the Industry in Battery Durability

While modern EVs generally demonstrate exceptional battery resilience, Kia and Hyundai set the gold standard in battery longevity and thermal management efficiency.

Out of dozens of tested models, the top three positions were dominated entirely by the Hyundai Motor Group:

1. Kia e-Niro (64 kWh): 97.25% state of health (SoH) after 100,000 km

2. Hyundai Kona Electric (64 kWh): 97.18% state of health (SoH) after 100,000 km

3. Kia EV6 (77.4 kWh): 95.95% state of health (SoH) after 100,000 km

These three models are the only vehicles in the entire study to retain over 95% to 97% of their original battery capacity after crossing 100,000 km.

Losing less than 3% to 4% of total capacity after heavy usage substantially outperforms conventional market expectations and highlights the strength of Hyundai and Kia's battery pack architectures, cell cooling designs, and Battery Management Systems (BMS).

Top 20 Electric Cars with the Highest Battery Health After 100,000 km (62,000 Miles)

1. Kia e-Niro (64 kWh): 97.25%

1. Hyundai Kona Electric (64 kWh): 97.18%

1. Kia EV6 (77.4 kWh): 95.95%

1. Volvo XC40 Recharge (69 kWh – CATL): 94.70%

1. Polestar 2 (78 kWh – CATL): 94.35%

1. BMW i3 (120 Ah): 93.77%

1. Polestar 2 (78 kWh – LG Chem): 93.53%

1. Tesla Model 3 (60.5 kWh – CATL LFP): 93.34%

1. Audi e-tron 50 (71 kWh): 93.02%

1. Audi e-tron 55 (95 kWh): 92.93%

1. Skoda Enyaq iV (77 kWh – SW 3.x.x): 92.88%

1. Tesla Model 3 (78.8 kWh – LG Chem – new SW): 92.83%

1. Tesla Model S (96 cells): 92.80%

1. Volkswagen ID.4 (77 kWh): 92.77%

1. Skoda Enyaq iV (77 kWh): 92.60%

1. Tesla Model X (96 cells): 92.52%

1. Volkswagen ID.4 (77 kWh – SW 3.x.x): 92.27%

1. Tesla Model Y (78.8 kWh – LG Chem): 92.18%

1. Audi Q4 e-tron (77 kWh): 92.18%

1. Volkswagen ID.3 (58 kWh): 91.79%

Why Battery Chemistry and Supplier Matter: The Tesla Case Study

The study highlights that battery performance does not depend solely on the car brand—the cell supplier and chemical composition play an equally vital role.

Looking at the Tesla Model 3, degradation figures varied significantly based on pack design and chemistry after 100,000 km:

• CATL (LFP / Lithium Iron Phosphate): 93.3% battery health

• LG Chem: 91.5% battery health

• Panasonic (77.8 kWh): 89.8% battery health

• Panasonic (52.4 kWh): 88.2% battery health

This variance underscores that pack thermal control, chemical cell structure (such as LFP vs. NMC), and pack buffer margins are decisive factors for long-term health.

What Does This Mean for Used Electric Car Buyers?

• Modern EV Batteries Last Longer Than Feared: Even lower-ranking mainstream models typically retain over 90% capacity after 100,000 km.

• Kia and Hyundai Offer Best-in-Class Value Retention: Buyers looking for maximum peace of mind regarding real-world range and minimal degradation will find used Kia and Hyundai models (like the e-Niro, Kona Electric, and EV6) among the safest, most durable choices available.

• Diagnostic Health Checks are Key: Because battery health varies between individual vehicle configurations and charging histories, obtaining a certified battery health diagnostic report (such as AVILOO) remains an essential step alongside inspecting mileage, service history, and model year.

About the Study Methodology

• Data Scope: 9,954 independent battery diagnostic tests carried out in Sweden between 2022 and 2026.

• Testing Standard: Performed using AVILOO battery diagnostics, evaluating high-voltage battery state of health (SoH) under standardized conditions.

• Reliability Filter: To ensure statistical accuracy, only vehicle models and battery configurations with statistically representative sample volumes were included in the final rankings.