High-mileage electric cars are failing fewer MOTs than petrol cars — what NI used-car buyers should actually take from the data

High mileage has always made used-car buyers nervous, but new analysis of 47.4 million MOT tests suggests the traditional “60,000 miles means trouble” shortcut may be less useful for electric cars.

The study, commissioned by the British Vehicle Rental and Leasing Association and carried out by New AutoMotive, found that electric and petrol cars had broadly similar MOT failure rates at lower mileages once age and mileage were controlled for.

Beyond about 60,000 miles, the pattern changed. EV failure rates levelled off at around 16%, while petrol and diesel failure rates continued to rise.

The headline numbers

Among cars aged three to eight years with between 90,000 and 120,000 miles recorded, 16.5% of EVs failed compared with 22.1% of petrol cars.

Above 120,000 miles, the study reported a 16.0% EV failure rate versus 23.5% for petrol cars.

That is useful evidence against the assumption that a high-mileage EV is automatically worn out.

But this is not Northern Ireland MOT data

The underlying analysis uses DVSA MOT records, which relate to Great Britain. Northern Ireland's vehicle testing system is operated by DVA.

That means PureCar is not presenting the percentages as an NI-specific MOT failure rate. The research is relevant to NI buyers because the same vehicle models and powertrain technologies are sold here, but the dataset itself is not a Northern Ireland sample.

An MOT does not tell you battery health

This is the biggest limitation and it is explicitly acknowledged by the researchers.

An MOT examines statutory roadworthiness items. It does not measure battery state of health, remaining usable capacity, charging speed, cell imbalance, software problems or the likelihood of an expensive battery-related repair.

A used EV can therefore have an excellent MOT history and still deserve a proper battery-health check.

EVs were not better at everything

The study found more tyre defects among electric cars — approximately 1.8 times as many as petrol cars across the dataset.

Researchers did not find the expected suspension penalty from EV weight. At 60,000 to 90,000 miles, the study recorded 4.7 suspension defects per 100 EV tests compared with 6.1 for petrol cars.

Regenerative braking also produced a mixed picture. High-mileage EVs had fewer brake defects, while some older low-mileage EVs showed more friction-brake problems, which researchers linked to corrosion when physical brakes are used less often.

What should an NI buyer check on a high-mileage EV?

• Battery health: seek a credible state-of-health reading where the manufacturer or a specialist can provide one.
• Battery warranty: check the exact time, mileage and capacity-retention conditions.
• Rapid-charging performance: confirm the car charges correctly rather than trusting the dashboard range figure.
• Tyres: inspect tread, sidewalls and uneven wear carefully.
• Brake condition: especially on cars that have spent long periods doing low mileage.
• MOT/test history: look for recurring defects and mileage consistency.
• Service history and recalls: check manufacturer campaigns and software updates.

PureCar's used-car buying checklist for Northern Ireland covers the broader paperwork and history checks that still apply to EVs.

Do not over-correct

The wrong conclusion would be “high-mileage EVs are always more reliable than petrol cars”. The study does not establish that.

It shows that, in a very large MOT dataset, high-mileage EVs were less likely to record a failing roadworthiness defect than comparable petrol cars once age and mileage were taken into account.

That is strong evidence that mileage alone is a poor reason to reject a used EV. Condition, battery health, history, warranty and price still decide whether the individual car is worth buying.

Source

BVRLA / New AutoMotive, September 2026. The research analysed 47.4 million DVSA MOT tests.