Electric Car MOT: What Is Tested, What Is Not, and What Actually Fails

The electric car arrived with a reputation for having almost nothing to go wrong. No oil, no clutch, no exhaust, no timing belt, and a fraction of the moving parts of a combustion engine. It would be reasonable to assume that a machine like that would breeze through an annual inspection designed, in large part, around the failings of petrol and diesel cars.

The rules do not make that assumption, and neither does the data. An electric car is tested on the same timetable and in the same class as any other car. Two chapters of the test fall away because there is nothing to inspect, and the one component owners care about most is barely looked at. What remains is a test of the things that carry, stop and steer a heavy vehicle, and it is on those things that electric cars are, on the evidence of the national test record, slightly more likely to be found wanting than petrol and diesel cars of the same age.

The rule: same schedule, same class, no exemption

An electric car needs its first MOT on the third anniversary of its first registration and a fresh test every year after that. That is exactly the schedule that applies to a petrol or diesel car. There is no electric exemption, no extended first-test interval for low-emission vehicles and no separate electric test.

Electric cars fall into MOT test class 4, alongside ordinary cars, light vans, motor caravans and taxis. The tester works from the same inspection manual and the same standardised procedure, records the result on the same DVSA system, and issues the same certificate. When you look a registration up on the MOT history check, an electric car's record appears in the same format as everyone else's, with the same categories of dangerous, major and minor defects and the same advisories.

The consequences of missing the date are also identical. Driving without a valid certificate is an offence in its own right, the vehicle cannot be taxed, and an insurer may take a different view of a claim if the car should have been tested and was not. The only lawful journeys without a certificate are to a pre-booked test, or to or from a garage for repairs.

Where confusion arises, it usually comes from one of two directions. The first is the assumption that because electric cars are new, they must be too new to need testing, which is true only until the third birthday. The second is a muddle with the genuinely exempt categories in the rules, which are set out in MOT exemptions explained. None of those categories covers an electric car.

What is not tested: emissions, and the battery

The largest procedural difference between an electric car's MOT and a petrol car's is the part that does not happen. A pure electric car has no exhaust, so there is no metered emissions test. The tester does not warm the car to operating temperature, does not put a probe in a tailpipe and does not measure carbon monoxide, hydrocarbons, lambda or smoke opacity. The visual inspection of the exhaust system, its mountings and its silencing is omitted too, since there is nothing to inspect. What happens instead on a petrol or diesel car is described in the MOT emissions test explained, and it is one of the more common reasons for an older combustion car to fail. That whole category of failure is closed to an electric car.

Plug-in hybrids sit on the other side of this line. They carry a combustion engine and are emissions tested according to the fuel that engine uses, and everything else about their test follows the petrol or diesel procedure.

The second omission is the one that surprises owners. The MOT does not test the traction battery in any meaningful sense. There is no capacity test, no load test, no measurement of state of health, no assessment of range and no check on whether the car charges properly at any speed. The tester does not plug anything into the car's diagnostic port to read battery data and is not asked to. The charging port, the charging cable and the on-board charger are not part of the inspection.

What the tester does do is look. The high-voltage system, which is almost always identifiable by its orange cabling, is inspected visually for cabling and components that are obviously damaged, insecure, chafed or poorly insulated, and for a battery casing that is visibly deformed or leaking. That is a safety check on the physical condition of the installation, not a test of its performance. It is carried out alongside the ordinary check that a vehicle's electrical wiring and battery are secure and undamaged, and testers are trained not to touch or disturb high-voltage components.

It follows that an MOT pass tells you nothing about the condition of an electric car's battery. A car whose battery has lost a substantial fraction of its original capacity, or which refuses to charge at anything like its rated speed, will pass in exactly the same way as a car with a battery in perfect health, provided the rest of the vehicle is in order. Anyone buying a used electric car who reads a clean MOT history as evidence of battery condition is reading something that is not there. Battery health has to be established separately, through the car's own diagnostics, a specialist report or a charging test over a decent distance.

What the tester does look at on an electric car

Everything else is tested exactly as it is on any other car. The full list is set out in what is checked on an MOT, and an electric car is subject to all of it: tyres and wheels, brakes, suspension, steering, lights and their alignment, wipers and washers, the windscreen, seatbelts and their anchorages, mirrors, the horn, the body structure and its resistance to corrosion, the registration plates, and the warning lamps for the braking, steering, airbag and tyre pressure systems.

A few of those items take on a different character on an electric car, and it helps to know which.

Brakes are tested on a roller brake tester in the usual way, measuring the effort at each wheel and the balance across each axle. Regenerative braking plays no part in this. The rollers measure what the friction brakes do when the pedal is pressed, and a car that slows beautifully on its motor alone can still fail if its discs and pads are not up to the job when asked. Where a car's drivetrain will not tolerate a roller test, and some dual-motor cars fall into this category, the tester uses a decelerometer on the road instead, exactly as with a permanent four-wheel-drive petrol car.

Tyres are checked for tread depth, condition and damage, and for being of a suitable size, type and load rating for the vehicle. That last point matters more on an electric car than on most, because the weight of the battery means many models are specified with reinforced tyres, and a replacement with too low a load rating is a defect in its own right.

The warning lamps are checked too. The MOT does not include any check of whether the car is reporting a high-voltage fault, but a tyre pressure monitoring warning that indicates a malfunction, on a car first used from 2012 onwards, is recorded as a defect and, where the system is judged inoperative, a failure. Electric cars, with their sensitivity to pressure and their large tyres, throw these warnings readily.

The structural inspection is unchanged. Electric cars are not immune to corrosion, and while the battery case protects a large area of the underside, the sills, subframes, suspension mountings and brake pipes are exposed as they are on any other vehicle. Some manufacturers use aluminium extensively in the body and suspension, which corrodes differently from steel but is not exempt from the tester's attention.

The finding: same-age electric cars pass slightly less often

The MOT Files has analysed the DVSA's anonymised record of 33 million class 4 MOT tests to see how electric cars actually fare. The analysis covers 51 electric models and 489,247 individual tests of electric cars.

Comparing electric cars with petrol and diesel cars is not as simple as taking two averages. The electric fleet is very young. The great majority of electric cars that have been presented for an MOT were between three and five years old at the time, whereas the petrol and diesel fleet stretches back decades and includes a great many cars whose problems have as much to do with age as with design. A raw comparison would flatter electric cars enormously and tell you nothing useful.

The comparison throughout is therefore between electric cars aged three to five years and petrol and diesel cars of the same age. That is the only fair contest, and it produces a result most people do not expect.

Between three and five years old, electric cars pass 86.7% of their MOT tests. Petrol and diesel cars of the same age pass 89.9%. Electric cars pass 3.2 percentage points less often.

That is the counter-intuitive headline. A category of vehicle with no emissions test to fail, far fewer moving parts and a reputation for needing little maintenance fails its MOT more often than same-age petrol and diesel cars. The gap is not enormous, and it is not evidence that electric cars are badly built. It is evidence that the MOT tests a particular set of things, and that electric cars are hard on exactly those things. The full model-by-model ranking is on the electric car MOT hub.

The spread between models is wide. Among cars aged three to five years, the Jaguar I-Pace records the highest pass rate of any electric model, at 92.0%, above the same-age petrol and diesel average. At the other end of the table, the Tesla Model X sits lowest among cars, at 79.1%. Both are large, heavy, powerful vehicles, which is a useful reminder that weight and torque are not a complete explanation on their own. Design, tyre specification, how a model tends to be driven and how well it tends to be maintained all play a part, and the differences between individual models are larger than the difference between electric cars and combustion cars as a whole.

Where the failures come from: tyres and suspension

A failed MOT is recorded as a list of defects, and one test can carry several. A car presented with two worn tyres and a split bush has three items on its sheet. The clearest way to compare where failures come from is therefore to count how many items of each kind appear per 100 failed tests, rather than to talk about a percentage of tests, and on that measure the four categories that matter look like this for cars aged three to five years.

Tyres dominate the electric picture. Tyre-related items are recorded 92 times per 100 failed electric-car tests, against 57 per 100 for petrol and diesel cars of the same age. That is not quite double, but it is a very large gap for a component whose legal requirements are identical across all cars.

Some of this is composition. Because electric cars have no emissions or engine items on their failure sheets, the other categories inevitably form a larger share of what is left. But engine and emissions items run at only around 4 per 100 failed tests on same-age combustion cars, and removing them does not come close to explaining a jump from 57 to 92. The difference is real, and it has a physical cause.

An electric car is heavy. The battery pack alone can weigh around half a tonne, and a family-sized electric car commonly weighs several hundred kilograms more than a petrol car of similar size and shape, often around a quarter to a third more. Every one of those kilograms is carried by four patches of rubber, and the load concentrates on the tyres' shoulders in every corner. At the same time, an electric motor delivers its full torque from a standstill, without the build-up a petrol engine goes through as it climbs through its revs. Pull away briskly from a junction and the driven tyres are asked to transmit a great deal of force instantly, every time, whether or not the driver intends anything dramatic. Rear-driven cars tend to wear their rear pair first; front-driven cars scrub their fronts.

The result is tyres that reach the legal limit sooner than the owner expects, and a pattern of wear that owners often miss. Inner-shoulder wear, where the tread is fine across the visible outer three-quarters of the tyre but has gone through to the cords on the inside edge, is common on heavy cars with pronounced suspension geometry. It is invisible unless you turn the wheel to full lock or get underneath, and it is the origin of a great many of the tyre ply or cord exposed failures in the record. That is a dangerous defect, and a car carrying one may not be driven away until the tyre is replaced. Less dramatically, tyre close to the legal limit is one of the most frequent advisories on electric cars, and it is the advisory that turns into a failure by the following year if nothing is done.

Suspension is the second part of the story, and in proportional terms the larger one. Suspension items are recorded 28 times per 100 failed electric-car tests, against 9 per 100 for same-age petrol and diesel cars, roughly three times the rate. Within that category, the single defect described as a suspension pin, bush or joint excessively worn is recorded about nine times more often on electric cars than on same-age petrol cars.

The explanation is the same weight and the same torque, acting on rubber and steel rather than on tread. Suspension bushes are compliant mountings that let the arms move while absorbing vibration. They are sized for the loads the designer expected, and a heavy car that accelerates hard and slows hard through its motor works them constantly. Bushes soften, split and go oval; ball joints develop play. None of this is dangerous in its early stages, and the car may drive perfectly well, but a tester levering a wheel and watching for movement will find it. The suspension arm bush worn entry describes what the tester is looking for and how the defect is graded.

There is a compounding effect between the two. Worn bushes let the wheel alignment wander under load, and wandering alignment eats tyres, particularly on the inner shoulder. A car with a suspension advisory at one test and a tyre failure at the next is following a well-worn path.

You can see how any individual model behaves on its own page. The Tesla Model 3 and Tesla Model Y, two of the most numerous electric cars on British roads, are a good place to start.

Where electric cars genuinely win: brakes and emissions

The picture is not one-sided. On two parts of the test, electric cars are in a different and better position from same-age petrol and diesel cars.

The first follows directly from the absence of an exhaust. Engine and emissions items are recorded at essentially zero per 100 failed electric-car tests, because there is nothing to record, against around 4 per 100 for same-age combustion cars. That category includes exhaust leaks, missing or defective emissions control equipment and readings over the limit, and an electric car is exposed to none of it. On older combustion cars the figure rises steeply, so the advantage widens as a fleet ages, but the same-age comparison is the honest one.

The second is braking. Brake items are recorded 10 times per 100 failed electric-car tests, against 29 per 100 for same-age petrol and diesel cars, about a third of the rate. This is the largest advantage electric cars hold anywhere in the test, and the reason is regenerative braking.

In an electric car, the motor that drives the wheels can be run as a generator. Lift off the accelerator and the car slows because the motor is converting its momentum back into charge, with the friction brakes not involved at all. In most electric cars a large proportion of everyday braking, from the gentle slowing on the approach to a roundabout to the last few miles per hour before a stop, is done this way. The friction brakes are reserved for firm stops and emergencies. Pads and discs that would wear out within a few years on a petrol car can, on an electric car, last far longer.

Set against the 92 tyre items and 28 suspension items, the brake and emissions figures make the overall result intelligible. Electric cars fail less on the parts of the test they barely use and more on the parts they use hardest. The net effect, at three to five years, is a pass rate a little below the petrol and diesel norm. The broader question of how electric cars are holding up beyond the test result is covered in the reliability study, which looks at the whole record rather than the pass rate alone.

Regenerative braking and the corroded disc

The brake advantage carries a small sting, and it appears on almost every electric car's MOT record sooner or later.

A brake disc that is used regularly is kept clean by its pads. Each application scrapes the friction surface, removes the light surface rust that forms overnight in damp weather and leaves the disc bright. A disc that is rarely used does not get this treatment. Surface rust that would ordinarily be wiped away at the first junction stays put, thickens and begins to pit the face of the disc. Salt on winter roads accelerates it. Given long enough, the friction surface becomes rough and uneven, and a lip of rust forms at the outer edge where the pad never reaches.

On a petrol car, discs are replaced because they have worn thin. On an electric car, they are more likely to be replaced because they have corroded while barely wearing at all. It is a genuinely different failure mode, and a low-mileage electric car used mainly for short urban journeys, with regeneration set to its strongest level, is the most exposed to it.

The MOT catches it in two ways. Most often, the tester records an advisory, usually in the classic wording that a disc is worn, pitted or scored but not seriously weakened. That is a warning rather than a failure, and it is the most common brake-related note on electric cars. Less often, corrosion is bad enough to affect the brake test itself. A heavily pitted disc grips unevenly, and the roller brake tester picks this up as a fluctuation in braking effort or as an imbalance between the two sides of an axle, both of which can be graded as a failure. Where a disc is seriously weakened, or a pad is contaminated or worn to its backing, the defect is graded as a failure in the ordinary way. The brake discs worn entry covers how the tester distinguishes between these.

The remedy is inelegant but effective. The friction brakes need to be used, firmly, from time to time. A few deliberate hard stops from moderate speed on an empty road, repeated every few weeks, will keep the discs clean. Many electric cars offer a setting that reduces regenerative braking and obliges the driver to use the pedal, and switching to it for a day now and again does the same job. Owners who never do either tend to arrive at their first MOT with an advisory they could have avoided, and at a later one with a disc that needs replacing despite having done a fraction of the work a petrol car's disc would have done in the same time.

Before the test: what an electric car owner should check

Most electric-car MOT failures are visible to an attentive owner a week before the test, and almost all of them are easier to deal with on your own terms than under pressure with an expired certificate. A sensible check runs in the order in which electric cars actually fail.

1. Tyres. Check the tread depth across the full width of each tyre, not just the visible outer edge, and turn the steering to full lock to see the inner shoulders of the front pair. The legal minimum is 1.6mm across the central three-quarters of the tread, around the whole circumference. Check that all four tyres carry the load rating the manufacturer specifies and that pressures match the placard, since electric cars usually run higher pressures than owners expect.
2. Suspension. Listen for knocks over speed humps and rough surfaces, and look for uneven tyre wear, which is often the first outward sign of a worn bush.
3. Brakes. Look at the discs through the wheel spokes. A bright, even face is fine; a brown or pitted one with a rusty lip is an advisory in waiting. Use the brakes firmly a few times on a clear road in the days before the test.
4. Lights, wipers, washers and horn. These fail electric cars for the same mundane reasons they fail every other car. Many electric cars use LED lamp units in which a failed element cannot be replaced individually, so a fault found the day before the test is not a quick fix.
5. Windscreen and warning lamps. A chip larger than 10mm in the area swept by the wipers directly in front of the driver is a failure, as is one larger than 40mm elsewhere in the swept area. Any lamp that stays lit for the brakes, airbag, power steering, stability control or tyre pressures needs attention before the test rather than after.

Two further points are peculiar to electric cars. The car needs enough charge to be driven onto the lift and the brake rollers and, if necessary, around the block for a decelerometer test. It also needs a healthy 12-volt auxiliary battery so that it wakes up when asked. Electric cars strand themselves on a flat 12-volt battery more often than owners expect, and a car that will not switch on cannot be tested.

None of this is specialist work. The tester is not going to examine the traction battery, so there is no point in worrying about it before the test. The things that fail electric cars are the things you can see by walking round the car and getting down on one knee.

A note on electric vans

Electric vans deserve a separate word because they fare worst of anything in the data, and because the one genuine electric exemption in the MOT rules concerns them rather than cars.

Among electric vehicles aged three to five years, the lowest pass rates in the analysis belong to vans. The Nissan e-NV200 passes 74.9% of its tests and the Maxus e Deliver 3 passes 71.5%. Both are light enough to be driven on an ordinary car licence and tested in class 4, so they appear in the same data as cars, and both sit well below the lowest-ranked electric car. The pattern of their failures is the car pattern, amplified. Vans carry payload on top of battery weight, they cover high mileages on delivery work with constant stopping and starting, they are driven by many hands, and they are kerbed. Tyres, suspension bushes and lamps take the consequences. Electric vans are also, in the main, run to schedules that leave little room for preventive attention, which is the same reason vans of any fuel type tend to fail more often than cars.

The exemption is narrow and often misread. Goods vehicles powered by electricity and registered before 1 March 2015 do not need an MOT. That covers a small and ageing population of early electric vans, and it does not extend to cars of any age or to any van registered after that date. An early e-NV200 registered before it is exempt; one registered a month later is tested annually from its third birthday like everything else. The other exempt categories are set out in MOT exemptions explained, and none of them has anything to do with how a vehicle is powered.

The short version

An electric car needs an MOT from its third birthday and every year after that, on exactly the same footing as a petrol car, as a class 4 vehicle, with no exemption. The test omits the emissions check because there is no exhaust, and it does not measure the battery's health, range or charging in any way. The tester looks at the high-voltage installation for visible damage and nothing more, and a pass says nothing about the battery.

Everything else is inspected as normal, and it is on the normal things that electric cars stumble. At three to five years old they pass 86.7% of tests against 89.9% for same-age petrol and diesel cars, and the difference is made almost entirely of tyres and suspension, the parts that bear the weight and the torque. Brakes and emissions run strongly the other way. Owners who watch their tyre shoulders, listen for worn bushes and use their friction brakes occasionally will find the test as undramatic as it should be. The full model-by-model figures are on the electric car MOT hub.