EV Journey

For years, battery degradation has been the biggest anxiety for anyone considering a used electric vehicle. The fear is a familiar one: buy an EV, watch its range quietly shrink, and end up with a car that can barely make the school run. The real-world data collected through 2026, however, tells a much calmer story — and it also makes clear that not all batteries age the same way.

The headline number: most EVs lose less than 10%
The most detailed dataset on this question comes from Carla, a Swedish used-car marketplace that compiled nearly 10,000 individual battery health tests carried out between 2022 and 2026, all measured at the 100,000 km mark. Across the top 20 models in the study, capacity loss stayed under 10%, and even the worst-performing car in that top tier — the Volkswagen ID.3 — still retained close to 92% of its original capacity.

Broader aggregations back this up. One compilation drawing on nearly 500 reference degradation curves across 46 models put the average state of health at 100,000 km at roughly 92%, with the median close behind — meaning half of all EVs on the road retain more than 92% of their original battery capacity by that mileage. That works out to an average loss of well under 1% for every 10,000 km driven.

The best performers

Two Korean EVs stand out clearly from the pack. In the Carla study, the Kia e-Niro (sold as the Niro Electric in the US) topped the rankings with 97.25% of its original capacity retained at 100,000 km, narrowly ahead of its mechanical sibling, the Hyundai Kona Electric, at 97.18%. That’s under 3% degradation — an exceptional result for cars that have covered real-world mileage rather than lab-controlled cycles.

Rounding out the leaders:

• Kia EV6 — 95.95% (77.4 kWh pack)
• Volvo XC40 Recharge — 94.70%
• Polestar 2 — 94.35%
• BMW i3 (42.2 kWh) — 93.77%

Other datasets point to a similar cluster of strong performers, including the Lucid Air, Hyundai Ioniq 6, and Mercedes EQS, each landing in the 93–94% range at 100,000 km in separate aggregated studies. Tesla’s Model 3 and Model Y also perform well, with LFP-chemistry versions retaining around 92% and NCA versions around 90% at comparable mileage, according to crowd-sourced fleet data.

Why the Korean EVs did so well

It’s a little counterintuitive that two older, first-generation EVs would outperform newer models with more advanced battery chemistry. A few factors likely explain it:

• Lower charging speeds. Both the e-Niro and Kona Electric charge at under 80 kW, which generates less heat and current stress than the 150–350 kW rates common in newer 800-volt platforms — and heat is the single biggest driver of long-term degradation.
• Liquid cooling. Both use actively cooled packs, which matters enormously; the study’s data reinforces the well-established pattern that thermally managed batteries age far more gracefully than passively cooled ones.
• Climate. Sweden’s cooler climate may have helped reduce degradation across the board, though this should apply fairly evenly to all cars in the sample.

Notably, the Kia EV6 — which charges roughly three times faster thanks to its 800-volt architecture — still came close to matching the slower-charging Korean siblings, suggesting that fast-charging capability alone isn’t the degradation death sentence it’s sometimes made out to be.

The cautionary tale: the Nissan Leaf

If there’s one model that consistently drags down the averages, it’s the early Nissan Leaf. Multiple independent datasets flag it as an outlier, with retained capacity around 82–83% at 100,000 km — nearly ten percentage points below the field average. The reason is well documented: the Leaf’s early packs used passive air cooling instead of active liquid cooling, leaving cells more exposed to heat buildup during fast charging and hot weather. It’s become the reference case for why thermal management matters so much in EV design.

What actually drives degradation

Across the various 2026 studies, a consistent set of factors emerges as the real drivers of capacity loss:

1. Heat exposure — both from climate and from charging. Fast charging above 100 kW for a large share of sessions roughly doubles the annual degradation rate compared with mostly AC/Level 2 charging.
2. Thermal management design — liquid-cooled packs consistently outperform air-cooled ones by a wide margin.
3. Climate — vehicles in hot climates degrade meaningfully faster (on the order of 0.4 percentage points per year) than those in milder regions.
4. Charging habits — frequent DC fast charging adds a modest but real degradation penalty, generally cited in the low single digits over 100,000 km/miles for heavy users, rather than the catastrophic losses once feared.

The takeaway for buyers

The data increasingly undercuts the old fear that EV batteries fall off a cliff. Manufacturers typically warranty batteries to at least 70% state of health over 8 years or 100,000 miles, and the real-world numbers suggest most cars comfortably beat that floor. If you’re shopping used, the practical advice is: look past raw mileage and ask for (or independently test) the battery’s actual state of health — a well-cared-for car with 100,000 km on a liquid-cooled pack can easily out-perform a low-mileage car that’s spent its life on rapid chargers in a hot climate.