The Austrian diagnostics company AVILOO has revealed the results of more than 500,000 tests of used electric-vehicle batteries, in one of the broadest independent studies announced to date. The study covered 20 popular models over distances of up to 150,000 kilometers, or approximately 93,000 miles. The Mercedes EQA, Hyundai IONIQ 5, and BMW i4 topped the list of cars that retained the highest level of battery health.
The study measures what it calls State of Health (SoH), which is the percentage of usable capacity remaining compared with the original capacity. At 150,000 kilometers, the Mercedes EQA recorded a median of 94%, followed by the Hyundai IONIQ 5 at 93.8%, and then the BMW i4 at 93.6%. The Hyundai Kona EV and Volvo XC40 Recharge were among the top five, with each exceeding 92.7%.
Strong Results at High Mileage
The IONIQ 5 was not only at the top at the highest mileage; it recorded the best result at 50,000 kilometers, with a State of Health of 97.1%, before the German models overtook it at longer distances. These figures indicate that the best-performing batteries in the sample retained more than 93% of their health after the equivalent of 93,000 miles.
At the other end of the ranking, the Nissan Leaf recorded 86.7%, the MINI Cooper SE 87.1%, and the Renault Zoe 87.3% at 150,000 kilometers. AVILOO believes the common factor among these models is the use of small battery packs; a 40-kilowatt-hour battery needs more charging cycles to cover the same distance than a 78-kilowatt-hour battery. The MINI Cooper SE declined the most, falling seven percentage points between 50,000 and 150,000 kilometers.
The Tesla Model Y recorded 90.3%, while the Model 3 recorded 88.9%, placing them in the bottom third of the list. AVILOO notes that more recent data was more positive regarding the LFP packs used in some Tesla vehicles, but that data came from a separate study and does not change the ranking of this sample.
Why Is the Model Average Not Enough?
The most important limitation of the results is that the figures shown are statistical medians, not precise predictions for every car. The difference between the best and worst sample of the same model reached 13.5%, a gap that could translate into dozens of kilometers of driving range on a single charge. Therefore, two cars of the same IONIQ 5 model, with the same mileage, may actually differ in their remaining battery value.
In addition, reading battery health from the car’s display is not a standardized measure, because each manufacturer calculates it differently. In practice, this means that the model ranking is useful for forming an initial picture when buying a used electric car, but it cannot replace an independent test of the specific car being offered.
How Did AVILOO Conduct the Measurements?
AVILOO relied on the FLASH test, which takes approximately three minutes and connects to the vehicle’s OBD port. The test calculates State of Health using a statistical model trained on data from hundreds of thousands of used vehicles, rather than relying solely on the car’s own battery-management system reading. The company says its full database has exceeded one million tests in North and South America, Europe, Australia, and Asia, while the current study represents more than 500,000 tests.
Editorial reading: The results do not prove that all electric-vehicle batteries will retain the same percentage of capacity, but they weaken the idea that battery degradation makes buying a used electric car an inherently general risk. The practical change for the buyer is a shift in focus from the model’s reputation alone to the condition of the individual car, while important questions remain about differences in chemistries, production years, and the distribution of samples across markets—details that the source material does not fully present.