Tesla built its whole reputation on battery longevity. But the biggest used EV battery health study ever conducted just knocked it down a few pegs. Mercedes, Hyundai, and BMW all outlasted both the Model Y and Model 3 at high mileage. The gap isn’t small enough to hand-wave away.
The data comes from Austrian diagnostics company AVILOO, whose Certified EV Battery Report pulled from more than 500,000 independent battery tests on 20 popular EV models. The testing ran from 2022 through 2026. It covered North America, South America, Europe, Asia, and Australia. Instead of relying on each car’s own battery management system readout, AVILOO used an OBD-based tool called the FLASH Test.
What did the study actually measure?
AVILOO tracked median State of Health, or SoH, at three mileage checkpoints: 50,000 km, 100,000 km, and 150,000 km. SoH simply means the percentage of a battery’s original usable capacity that’s still there. A car sitting at 90% SoH can still cover 90% of the range it delivered when new.
That’s a meaningful distinction from range estimates you’d see on a used-car listing. Software buffers and efficiency tweaks can muddy those numbers. A raw SoH test strips that out and measures the pack itself.
Which EVs beat Tesla in battery health?
At the 150,000-km mark, roughly 93,000 miles, the Mercedes EQA led the entire field at 94% SoH. The Hyundai Ioniq 5 came in right behind at 93.8%. The BMW i4 was close too, at 93.6%. Tesla’s Model Y landed at 90.3%, and the Model 3 came in lower still at 88.9%.
That’s a real gap, not rounding error. Several other mainstream EVs also finished ahead of both Teslas at the same mileage. That list includes the Hyundai Kona Electric, Volvo XC40 Recharge, Ford Mustang Mach-E, and Polestar 2.
| Model | SoH at 150,000 km (~93,000 mi) |
|---|---|
| Mercedes EQA | 94.0% |
| Hyundai Ioniq 5 | 93.8% |
| BMW i4 | 93.6% |
| Hyundai Kona Electric | 93.0% |
| Volvo XC40 Recharge | 92.8% |
| Ford Mustang Mach-E | 92.5% |
| Polestar 2 | 92.5% |
| Tesla Model Y | 90.3% |
| Tesla Model 3 | 88.9% |
Cross-shopping a used Mach-E against a Model Y? This number is worth weighing before you sign anything. It’s also worth reading up on the Mach-E’s recall history, since battery health is only half the picture on any used EV.
Why did Tesla fall behind here?
Tesla didn’t do badly in absolute terms. But the sheer size of this dataset undercuts the old assumption that Tesla packs simply outlast everyone else’s by default. A smaller, earlier study out of Sweden had actually put the Model Y in third place overall. So this result is a genuine shift, not just noise from a tiny sample.
AVILOO’s own researchers are careful to note the gap isn’t catastrophic. Both Tesla models still retain the clear majority of their original range past 90,000 miles. A 90% or 89% SoH is a perfectly livable outcome for most daily drivers.
Which used EVs should you avoid?
Skip the smallest-battery EVs if long-term range retention matters to you. The Nissan Leaf, MINI Cooper SE, and Renault Zoe all finished at the bottom of the study. The common thread is pack size. A 40-kWh battery has to cycle through far more charges to cover the same distance as a 78-kWh one.
Those extra cycles add up. The MINI Cooper SE dropped a full seven points of SoH between 50,000 and 150,000 km, the steepest decline anywhere in the study. The Leaf finished lowest overall at 86.7%. Shopping in that segment? Read our Bolt vs. Leaf comparison before you commit to a small-pack EV.
Does this mean you shouldn’t buy a used Tesla?
No — a used Model 3 or Model Y at 88–90% SoH is still a solid buy, especially given how much cheaper used Teslas have gotten. But don’t assume the badge alone guarantees a better battery than the competition. Check the actual test results for the specific car.
That’s especially true given how much variation AVILOO found within individual models, not just between brands. Two Model Ys with identical mileage can land meaningfully apart in SoH. Charging habits and climate explain most of that gap. That’s exactly why a real battery diagnostic matters more than trusting the odometer. Weighing a used Tesla against anything else on this list? Our breakdown of recent Tesla recalls is worth a look too, since recall history and battery health are separate but equally important checks.
How should this change your used EV shopping?
Get an independent battery health test before you buy, full stop. Don’t rely on the seller’s word or a dashboard range estimate. This study proves brand reputation isn’t a reliable stand-in for an actual SoH reading. And the price of a diagnostic is nothing compared to a $10,000+ battery replacement.
Also pay attention to how the car was charged, not just how far it’s been driven. Frequent high-power DC fast charging accelerates degradation more than mileage does, according to Geotab’s own fleet-wide battery research. So a low-mileage car that’s been fast-charged constantly can actually be a worse bet than a higher-mileage one charged mostly at home.
For a full walkthrough of what else to check — recalls, warranty transferability, charging history, and negotiating leverage — see our full used EV buying guide before you make an offer.
FAQ
What is a good State of Health percentage for a used EV?
Anything above 90% SoH at typical used-car mileage (60,000–90,000 miles) is considered strong. Even the weakest performers in this study still sat around 87%. That’s a livable outcome, not a red flag on its own.
Is Tesla’s battery warranty still competitive?
Yes — federal law requires an 8-year, 100,000-mile minimum battery warranty on all EVs sold in the U.S. Tesla meets that standard. This study is about real-world degradation trends, not warranty coverage, which remains solid across the industry.
Does fast charging really damage EV batteries that much?
It’s the single biggest factor an owner controls. Heavy reliance on high-power DC fast charging can roughly double the annual degradation rate compared to mostly AC or slower charging. A car’s charging history matters more than raw mileage.
Should I get a battery test before buying a used EV?
Absolutely. A standalone diagnostic test costs far less than risking an inaccurate range estimate. It’s the only way to know a specific car’s actual battery condition rather than relying on the model’s average.