Dealers face sharply different battery-health and valuation risks across popular electric models, with the Nissan Leaf ZE1, Mini Cooper SE and Renault Zoe recording the lowest median capacity at higher mileages in a major study.
Aviloo analysed more than 500,000 battery tests conducted between 2022 and 2026, covering 20 popular EV models in markets across Europe, North and South America, Australia and Asia.
The findings show why dealerships cannot rely solely on mileage or model-level averages when sourcing and valuing used EV stock.
Vehicles of the same model can have substantially different battery health depending on their age, charging history, usage and operating climate.
For dealers, this introduces another valuation variable in a used EV market already exposed to rapid product development, changing incentives and fluctuations in vehicle supply.
Lowest battery health models
At 150,000km, equivalent to approximately 93,000 miles, the 40kWh Nissan Leaf ZE1 recorded the lowest median state of health in the study at 86.3%.
It was followed by the Mini Cooper SE at 87.1%, Renault Zoe at 87.3%, Tesla Model 3 at 88.9% and Tesla Model Y at 90.3%.
The Mini Cooper SE experienced the largest decline between the study’s 50,000km and 150,000km milestones. Its median battery health fell seven percentage points, from 94.1% to 87.1%.
The Nissan Leaf’s median result declined from 91.1% at 50,000km to 86.3% at 150,000km. Aviloo said its smaller battery capacity and associated charging frequency helped illustrate how different vehicle characteristics can influence degradation.
However, the results do not suggest that the batteries are approaching failure. Even the lowest-ranked models retained more than 86% of their original usable capacity at 150,000km.
Why dealer battery tests matter
The variation between individual examples of the same model could be more important to dealers than their position in the overall ranking.
The Nissan Leaf recorded a spread of up to 13.5 percentage points in state of health at 150,000km, equivalent to a difference of around 29km in real world range per charge.
Used EVs with identical ages and mileages could therefore have materially different usable ranges, desirability and values. This creates potential risks for dealerships when appraising part exchanges, purchasing stock, setting retail prices or underwriting warranties.
Vehicle-specific battery testing could also help dealers support advertised prices, demonstrate vehicle condition to customers and distinguish stronger examples from apparently similar stock.
Marcus Berger, chief executive of Aviloo, said: “The truth in this data is that averages hide a lot. Yes, EV batteries are ageing better than the ‘they wear out fast’ myth suggests – but that’s not the most useful thing this report tells you.
“What matters is that battery health varies significantly between models, and even more between individual cars of the same model. A gap of 10% or 15% in state of health is a real difference in range, in what a car is worth, and in what you can rely on it for. You simply can’t know where your car sits in that range without testing it independently.
“That’s why we built the Aviloo Flash Test, and why we’re now publishing this Aviloo Certified EV Battery Report twice a year – to give the whole market, from individual buyers to fleets and insurers, an honest, independent and genuinely global picture of how these batteries perform.”
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