The motor isn’t the part that quits

Pull the odometer data on any high-mileage EV and a pattern shows up fast: the battery is the component doing all the aging, while the motor mostly just sits there working. A Tesla Model S used as a Finnish taxi crossed 430,000 miles on its original drive unit with, according to the shop that inspected it, zero motor replacements and zero drivetrain services — while its battery had degraded to roughly 72% of its original capacity, a 28% loss after eight years of continuous ride-hailing use. That is not a fluke. Across the used-EV market, the drive motor is turning into the one part of the car nobody worries about, and the battery is turning into the one part everybody has to check.

The gap comes down to physics, not marketing. A permanent-magnet EV motor has essentially one moving part — a rotor spinning on a pair of bearings — with no pistons, no valvetrain, no combustion heat cycling, and no oil to break down. Bearing engineers who build EV-grade ceramic bearings describe wear intervals in the range of roughly 500,000 miles before the bearings themselves need attention — in other words, close to the entire realistic service life of the vehicle around it. A battery pack, by contrast, is a chemical device. Every charge cycle nudges its internal chemistry a little further from new, and that decline is measurable, linear, and unavoidable, no matter how well-engineered the pack is.

What the degradation data actually shows

Fleet telematics company Geotab tracked 22,700 EVs across 21 models and found average battery degradation of 2.3% per year, which works out to roughly 81.6% of original capacity remaining after eight years — with older, more mature battery chemistries stabilizing closer to 1.4% per year. EV data firm Recurrent, drawing on 15,000 vehicles and 250 million miles of real-world driving, found that outright battery replacements due to failure remain rare — about 1.5% of packs outside of recalls, and well under 1% for 2016-and-newer model years, per the U.S. Department of Energy’s own tracking of that dataset. Rare is not zero, though, and it is a number with no real motor-side equivalent in the same research — nobody is tracking a comparable “motor replacement rate” because there’s so little to track.

High-mileage case studies back this up in a more granular way. The Tesloop shuttle fleet, which ran Model S sedans in commercial service, documented a front drive unit replacement on one car at just 36,000 miles — but that was a single, early, warranty-covered fix, and “no issues with the vehicle’s drive units have emerged since,” even as the same car went on to need two separate high-voltage battery pack replacements by 324,000 miles. One motor fix in the first year of hard service, followed by hundreds of thousands of trouble-free miles, against two full battery swaps — that is close to the cleanest real-world illustration of the gap you’ll find.

What this means if you’re shopping used

For decades, buying a high-mileage used car meant fixating on engine mileage, because the engine was the expensive, wear-prone heart of the machine that determined whether the car had years left in it. That logic does not transfer cleanly to EVs. A used EV with 120,000 miles on the odometer almost certainly has a drive motor with plenty of life left — the failure mode you actually need to worry about is battery state of health, not motor wear. That flips the entire used-EV inspection checklist: instead of a compression test or a listen for engine knock, the number that matters is the battery’s remaining capacity relative to when it left the factory, which several manufacturers and third-party services can now pull directly from the car’s own battery management system.

It also reshapes the economics of buying high-mileage. A gas car with a tired engine is often a write-off, because engine work is expensive and buyers assume the worst about everything else, too. A high-mileage EV with a strong-testing battery is arguably a better bet than the mileage number alone would suggest, since the part most likely to have been quietly wearing down for years is exactly the part you can test in a parking lot before you sign anything — while the part you can’t easily inspect, the motor, is statistically the one least likely to be the problem.

The number that should be on every used-EV listing

None of this means EV batteries are fragile — Recurrent’s own data says the opposite, with the vast majority of packs never needing replacement at all. What it means is that “battery” and “motor” have swapped roles from what a lifelong gas-car buyer expects: the complicated-sounding electrical component is turning out to be the simple, close-to-permanent part, while the “just a battery” is the one component with a real, measurable, unavoidable aging curve. Buyers who keep pricing high-mileage EVs the way they priced high-mileage Camrys — worried about the wrong part wearing out — are the ones most likely to either overpay for a tired pack or walk away from a genuinely good deal.