Can electric cars maintain reliable performance as age and mileage increase? A wide-ranging analysis of vehicle MOT data in the UK suggests the answer to this question may be contrary to common belief.
The review, carried out by New Automotive for the British Vehicle Rental and Leasing Association (BVRLA), examined data from 47.4 million vehicle MOT tests in the UK. The results show that electric cars have a lower failure rate than petrol cars of the same age at higher mileages.
Among cars that have done less than 60,000 miles (about 96,000 kilometres), no significant difference was observed between electric and petrol cars. But as mileage increases, the gap widened and in the 90,000 to 120,000 miles (about 145,000 to 193,000 kilometres) range, electric cars performed better in MOT tests.
In this range, 16.5 percent of electric cars failed the test, while the failure rate for petrol cars was 22.1 percent. Thus, the likelihood of electric cars failing in this bracket was reported to be about one quarter lower than petrol cars.
Why do electric cars perform better as mileage increases?
One main explanation relates to the simpler drivetrain architecture of electric cars. Battery-electric vehicles typically have fewer moving mechanical parts than internal combustion engine vehicles.
Toby Poston, chief executive of the BVRLA, explained that removing the internal combustion engine, exhaust system and conventional gearbox can reduce the number of parts that suffer mechanical wear over time.
In petrol cars, a collection of engine components, the transmission and exhaust are subject to heat, friction and continual movement over thousands of miles. Electric cars also have consumable parts and mechanical sections, but their drivetrain architecture is simpler.
This may explain why the difference between the two groups grows at higher mileages. However, according to Poston, the study’s result does not mean electric cars do not require maintenance; rather it challenges the notion that reaching 80,000 or 100,000 miles necessarily means a car is approaching the end of its useful life.
Mileage matters more than the car’s age
Another finding of the study is that mileage can be a better indicator of a vehicle’s condition than its age.
For example, a petrol car before its first mandatory MOT at three years had on average done around 20,499 miles (33,000 kilometres). That figure for electric cars was about 27,072 miles (43,000 kilometres).
This difference is important when comparing the two groups; because electric cars on the UK market are on average younger than petrol cars and yet some have covered greater distances.
Ben Nelmes of New Automotive also warned that a simple comparison of MOT pass rates cannot show the whole picture of reliability. Comparing cars of the same age can also be misleading, because electric cars have typically covered more miles.
An important point about the battery
Despite the breadth of this analysis, an important limitation exists: the UK MOT test does not assess the health of electric car batteries.
The test mainly checks parts such as brakes, tyres, suspension, steering and lights and does not directly measure battery condition or charging system performance.
This point is significant, because the battery is the most expensive and one of the most important components of electric cars, and its degradation can affect range, resale value and ownership cost.
Therefore the findings of this study should be seen more as an indicator of the reliability of the components inspected on the road, not as definitive evidence about the durability of every part of an electric vehicle.
Overall, the obtained data indicate that increased mileage does not necessarily mean a rapid rise in failures for electric cars and that even at high mileages these cars performed better than petrol examples in the parts examined in the MOT. However, to judge long-term durability of electric cars, a separate assessment of battery condition and maintenance costs is also necessary.