The message is clear: test your car independently, don't guess its health
Wiener Neudorf, September 2nd 2026: AVILOO, the global leader in EV battery diagnostics, has today launched its AVILOO Certified EV Battery Report– the world's largest independent study of battery health in used electric vehicles.
This edition analyses over 500,000 individual, independent tests carried out on used EVs between 2022 and 2026, covering 20 popular EV models. It draws on a subset of AVILOO's broader diagnostic database, which now spans more than 1 million independent tests worldwide across North and South America, Europe, Australia and Asia. AVILOO will publish the AVILOO Certified EV Battery Report twice a year.
The findings carry a clear message for anyone buying, selling, financing or insuring a used EV; don't assume your battery's health - test it independently. Every figure in this report comes from AVILOO's own physical measurement of the battery, not a reading taken from the vehicle's dashboard, which can vary from manufacturer to manufacturer and doesn't always reflect the battery's true condition. Overall battery health across the market remains strong, but AVILOO's data shows meaningful differences both between models and between individual examples of the same model - differences significant enough to change what a car is really worth.
How the report works
The AVILOO Certified EV Battery Report is built on data from used electric vehicles tested via its independent AVILOO FLASH Test. For each model, AVILOO calculates the median State of Health at three mileage milestones – 50,000 km, 100,000 km and 150,000 km – along with the range expected to cover 99% of vehicles at each point†.
State of Health (SoH) – the percentage of a battery's original usable capacity that remains – is the clearest single measure of how a used EV's battery has aged; a battery at 95% SoH still delivers roughly 95% of its original range per charge.
Reading the data
The charts below show real AVILOO FLASH Test results from used EVs, presented in alphabetical order, at each of the three mileage milestones. Each bar shows the expected range of battery health for that model at that mileage – the lower and upper numbers mark a 99% prediction intervals band and the black line marks the median result. The data also aggregates multiple battery sizes behind each vehicle model.
Comparing the three mileage snapshots side by side reveals three consistent patterns. First, median battery health drops as mileage increases. Second, the spread between individual cars widens with distance – degradation is real, and it grows the further a car travels. Third, and just as importantly, there are consistent differences between models at every mileage point
Four EVs, four different battery stories
The Tesla Model Y (78.8 kWh) has been the best-selling car of any kind, anywhere in the world, for three consecutive years*. In AVILOO's data, used Model Ys show a median State of Health of 94.5% at 50,000 km, falling to 90.3% at 150,000 km – equivalent to a real-world range per charge of around 379 km, dropping to roughly 362 km. That median is only the midpoint: individual cars vary by up to 11% of state of health across that range, worth around 46 km of real-world range per charge – a reminder that the model average doesn't tell you how any one car has actually aged.
The Volkswagen ID.4 (77 kWh) was one of Europe's top-selling EVs in 2025, with more than 40,000 units sold in the first half of the year alone**. Median battery health runs from 95.3% at 50,000 km to 90.6% at 150,000 km – a real-world range per charge of around 373 km, falling to roughly 354 km. Individual cars vary by up to 11-12% of state of health at higher mileages, worth around 45 km of real-world range per charge.
The Hyundai IONIQ 5 (72.6 kWh) has become one of the most recognisable EVs on our roads today. In AVILOO's data, median SoH runs from 97.2% at 50,000 km to 92.8% at 150,000 km – equivalent to a real-world range per charge of around 335 km, dropping to roughly 319 km. The spread between individual cars grows to over 12% of state of health by 150,000 km, worth around 42 km of real-world range per charge – a reminder that only an independent test tells you where a specific car sits.
The Nissan Leaf ZE1 (40 kWh) has the smallest battery of the four models here – around half the capacity of the others – needing far more frequent charging to cover the same distance. AVILOO's data shows the effect: median SoH falls from 91.1% at 50,000 km to 86.3% at 150,000 km, the lowest of the four models throughout, with the widest spread of any model here – up to 13.5% of state of health by 150,000 km, worth around 29 km of real-world range per charge.
In real-world terms, that median SoH is worth around 196 km of range per charge at 50,000 km, dropping to roughly 185 km at 150,000 km – markedly less than the other three models, reflecting its smaller battery and suiting it best to shorter, more local journeys. The Leaf remains the world's first mass-market EV, with more than 650,000 units sold worldwide***. It's the clearest illustration in this report of how battery size and charging frequency interact with real-world degradation – and why independent testing matters most for this kind of higher-use EV.
Why a small gap in state of health matters more than it sounds
As the examples above show, a gap of ten percent or more in state of health isn't just a number on a spec sheet – it can mean tens of kilometres of real-world range per charge. It can be the difference between a car that comfortably completes a long day trip and one that needs an extra charging stop. That's exactly the kind of detail a consumer, dealer or lender would want to know before a used EV changes hands – and exactly why a single average number for a whole model isn't enough.
Why climate matters – and why global data matters more
Battery health isn't just a function of mileage. Temperature affects both the chemistry of degradation and how quickly a battery can accept charge – cooler climates, for example, can slow charge rates and change wear patterns compared with warmer ones. That's why AVILOO's global reach matters: because the AVILOO Certified EV Battery Report draws on independent tests from across North and South America, Europe, Australia and Asia, its findings reflect a genuine spread of climates and driving conditions, rather than the pattern seen in any single country or region.
Why this matters for the used-EV market
That distinction matters more as the used-EV market grows. Buyers of a used petrol or diesel car have long relied on a mileage reading and an MOT history to judge condition; consumers, dealers and fleets buying a used EV need an equivalent for the battery – the single most expensive component in the car, and, as this report shows, the component most likely to vary from car to car.
Marcus Berger, CEO 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 ten or fifteen percent 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.”
AVILOO's FLASH Test, an independent, three-minute diagnostic performed via the vehicle's OBD port, is designed to answer that question for each individual used vehicle, rather than relying on an average across the model: a battery health certificate that gives consumers, dealers, fleet operators, insurers and lenders a trusted, independent number to work from, rather than the reading provided by the car's own dashboard.
Independent measurement, not a dashboard reading
What sets AVILOO's FLASH Test apart is that the number comes from independent measurement, not from the vehicle's own reporting. Rather than reading out a figure generated internally by the car's battery management system, AVILOO calculates SoH using a statistical model trained on hundreds of thousands of comparable, real, used vehicles. In addition to the car's internal health assessment, AVILOO also take into account battery State of Health (SoH), mileage, age, cycles, cell voltage spread, energy counts and multiple other diagnostic signals.
That independence matters to consumers and trade buyers alike – fleet managers, remarketers and insurers – who need a consistent, comparable measure of battery health across makes and models, rather than a figure that can vary depending on how a manufacturer's software chooses to report it.
AVILOO Battery Warranty launches across Europe
This summer, AVILOO launched its Battery Warranty across Europe, extending the diagnostics behind the FLASH Test into a genuine, financially backed guarantee on battery health for buyers of used electric vehicles – based entirely on independent diagnostic data rather than manufacturer claims.
For each vehicle, AVILOO uses its global diagnostics database to calculate an individual State of Health limit – the minimum the battery must maintain at 20,000 kilometres within the one-year warranty period. If the battery falls below that limit, buyers receive £2,700 in the UK ($3,600) and €3,000 in most European countries.
The guarantee is now live in the UK, Germany, the Netherlands, Finland, Austria, Belgium, Ireland, Switzerland, France, Sweden, Norway and Denmark.
Already trusted by Europe's biggest automotive names
AVILOO's credentials in battery diagnostics are already well established. Mercedes-Benz, Volvo, and Porsche Holding have each selected AVILOO as their preferred independent, third-party battery testing provider for dealerships across Europe, with the AVILOO FLASH Test deployed on both own-brand and trade-in vehicles.
Leasing majors Ayvens and Arval use AVILOO as part of their end-of-lease remarketing process. Auction groups BCA and Cox Automotive have integrated the AVILOO FLASH Test into their European operations. Major dealer groups Hedin and Emil Frey are also live. All relationships are underpinned by European-level agreements.
About AVILOO
AVILOO is the global leader in battery diagnostics for electric and plug-in hybrid vehicles. The company develops and markets precise, fast, and manufacturer-independent tests to detect the State of Health (SoH) and defects in drive batteries of used vehicles. Its test results are provided in detailed reports and certificates. All analysis methods and certificates are TÜV and CARA certified, ensuring complete transparency and safety for used car buyers, sellers, and users – both commercial and private. With the AVILOO FLASH Test, the company offers the only independent EV battery quick test on the market – not a BMS readout, but a genuine diagnostic that can be carried out cost-effectively and easily on the vehicle in just three minutes. AVILOO currently covers over 96% of all available brands. AVILOO's diagnostic database now spans more than 1 million independent tests carried out on used EVs across North and South America, Europe and Asia, and the company publishes its AVILOO Certified EV Battery Report twice a year to share insights from that data with the wider market.
Notes to editors
This report analyses a subset of AVILOO's global diagnostics database: over 500,000 individual, independent AVILOO FLASH Test results from used EVs tested between 2022 and 2026, drawn from vehicles across North and South America, Europe, Australia and Asia. AVILOO's total diagnostic database exceeds 1 million independent tests worldwide. Chart data: AVILOO FLASH test-weighted distribution, 99% confidence bands (α = 0.99), calculated at 50,000 km / 100,000 km / 150,000 km mileage buckets, covering 20 popular EV models presented in alphabetical order. The four vehicles explored in detail in this release – Tesla Model Y (78.8 kWh), Volkswagen ID.4 (77 kWh), Hyundai IONIQ 5 (72.6 kWh) and Nissan Leaf ZE1 (40 kWh) – are illustrative examples chosen to show a range of battery sizes and vehicle types, not an exhaustive list or a ranking.
† Methodology: for each vehicle model, independent AVILOO FLASH-test data is used to produce a statistical distribution of State of Health at each mileage point. The distribution is found by fitting multiple quantile curves, including the median, to the data.
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Sources
* Tesla Model Y: world's best-selling car of any kind for three consecutive years (2023-2025); cumulative global sales passed 4 million units. Source: CnEVPost, March 2026.
** Volkswagen ID.4: 40,335 units sold in Europe in the first half of 2025, the second best-selling EV model in Europe that half, up 38% year-on-year. Source: best-selling-cars.com, July 2025.
*** Nissan Leaf: first mass-market EV, launched December 2010; over 650,000 units sold worldwide as of November 2025. Source: Nissan.