High mileage electric cars are less likely to fail an MOT than equivalent petrol models, analysis of 47.4 million tests has found.
The findings could help dealers challenge customer concerns about stocking and buying used electric vehicles (EVs) with more than 60,000 miles on the clock.
Research commissioned by the British Vehicle Rental and Leasing Association (BVRLA) found that EV failure rates levelled off at around 16% from approximately 60,000 miles. Petrol and diesel failure rates continued to increase as mileage rose.
Among cars aged between three and eight years with 90,000 to 120,000 miles, 16.5% of EVs failed their MOT, compared with 22.1% of equivalent petrol cars.
This made the electric cars around 25% less likely to fail when both vehicle age and mileage were taken into account.
Above 120,000 miles, 16% of EVs failed, compared with 23.5% of petrol cars.
The study was conducted by transport research organisation New AutoMotive using official Driver and Vehicle Standards Agency (DVSA) MOT records.
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Similar performance at lower mileages
The researchers found relatively little difference between petrol and electric cars at lower mileages.
Between 20,000 and 40,000 miles, 12% of battery-electric cars failed their MOT, compared with 11.7% of petrol cars of the same age and mileage.
The gap began to emerge from around 60,000 miles, challenging the conventional used-car assumption that rising mileage is inevitably accompanied by a greater risk of mechanical problems.
BVRLA chief executive Toby Poston said: “Mileage has always been one of the first things people look at when buying a used car, and passing 60,000 or 70,000 miles can have a big impact on how a vehicle is perceived.
“This research suggests we need to think differently when it comes to electric vehicles.
“What this data shows is that mileage alone should not put consumers off. A well-maintained, higher-mileage electric car can be an extremely durable used vehicle.”
Many of the EVs now reaching dealer forecourts began their lives in company car and leasing fleets and may have accumulated substantial mileage before entering the used market.
Poston said building confidence in those vehicles would be important in making electric cars accessible to more used-car buyers.
Older EVs remain in use
The researchers also examined whether electric cars appeared to leave Britain’s roads earlier than petrol vehicles.
They tracked whether vehicles returned for another MOT within 30 months. At 15 years old, 94.6% of electric cars returned, compared with 88.1% of petrol cars.
This produced an implied road-exit rate of 5.4% for EVs and 11.9% for petrol cars.
However, the researchers cautioned that vehicles leaving the MOT dataset may have been exported, declared off the road or scrapped. The figures do not represent confirmed scrappage rates.
Older EVs were also not simply being retained as low-mileage second cars. Electric cars recorded higher median annual mileages than petrol cars at every age examined between four and 16 years.
At 12 years old, EVs covered a median of approximately 4,920 miles annually, compared with 4,410 miles for petrol cars.
New AutoMotive chief executive Ben Nelmes said controlling for both age and mileage was important because Britain’s EV population was considerably younger than its petrol and diesel fleet.
He added: “At lower mileages there is very little between petrol and electric cars, but beyond around 60,000 miles the failure rate for EVs flattens while the petrol failure rate continues to rise.”
Nelmes attributed the pattern partly to the mechanical simplicity of an electric drivetrain, which becomes increasingly relevant as vehicles accumulate mileage.
EVs record more tyre defects
The research did identify areas where EVs performed less strongly.
Electric cars recorded approximately 1.8 times as many tyre defects as petrol cars, with the problem particularly pronounced among some earlier EVs adapted from combustion-engine platforms.
However, the analysis found no equivalent suspension penalty associated with the additional weight of electric cars.
Between 60,000 and 90,000 miles, EVs recorded 4.7 suspension defects for every 100 tests, compared with 6.1 for petrol cars.
The effect of regenerative braking was more complicated. High-mileage EVs experienced substantially fewer brake defects, while older electric cars covering fewer miles recorded more friction-brake defects.
Researchers attributed the latter finding to corrosion caused by the physical brakes being used less frequently.
Hybrid cars also performed strongly and recorded lower MOT failure rates than petrol cars and battery-electric vehicles in several categories.
The researchers stressed that the study was not intended to establish one powertrain as universally more reliable. Its purpose was to examine concerns that EVs become less roadworthy as they age and accumulate mileage.
Battery condition not covered by MOT data
The analysis does not measure the condition or remaining capacity of an electric car’s battery.
An MOT examines statutory roadworthiness, including tyres, brakes, suspension, steering and lights. It does not assess battery state of health, degradation, charging performance, software problems or unscheduled warranty repairs.
Dealers and customers must therefore consider battery-health information alongside a used EV’s mechanical condition, mileage and maintenance history.
Poston added: “This isn’t an argument for buying a used EV without doing your homework. Buyers should look at its history, condition, tyres and battery health just as they would scrutinise the engine, gearbox and service history of a petrol or diesel car.
“What we can now challenge is the idea that an electric car with 80,000 or 100,000 miles on the clock should automatically be regarded as worn out. The evidence simply doesn’t support that assumption.”