BMW 3 Series 2018: reliability & common MOT faults

In 2025, 86 in every 100 first MOTs on a 2018 BMW 3 Series were passes. Most common reason for a fail: Tyre condition (rear).

Summary

The 2018 BMW 3 Series follows the pattern of the model years either side.

At a glance

How 23,137 first tests went in 2025.

Passed first time
86 in every 100
Did not pass first time
14 in every 1003,337 failed first-attempt tests
The typical car
7 yearsabout 63,863 miles
First tests counted
23,137

What failed most often

  1. Tyre condition (rear)19 in every 100 failed tests
  2. Tyre tread depth (rear)12 in every 100 failed tests
  3. Brake pads (rear)9 in every 100 failed tests

How we count this. Data: UK MOT open data, 2025. Only Class 4 cars on their first MOT of the year are counted. A car that fails and is fixed at the test station still counts as a fail in the first-attempt rate. These are raw results, not adjusted for age, mileage, or peer mix. The MOT does not test engine or gearbox internals.

Note:

These are patterns across 2018 BMW 3 Series vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. A wear pattern follows age and use more than the way the car was built. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.

Road wheels

One fault: wheel condition (rear), 11 times as often as on similar cars.

Figures below are measured across the 3,336 of 3,337 failed first attempts that recorded an odometer reading in 2025. Mileage is needed to compare like with like.

We only list faults with at least 20 failures and a rate of about 2.0 times that of similar cars, which keeps one-off results out of the list.

Wheel condition (rear)

Failed on 81 first tests11 times as often as similar carsLikely evidence

What it means

A wheel with any fracture or welding defect is graded Dangerous. So is a tyre retaining ring likely to come off, or a wheel distorted or worn to the extent that the wheel or tyre is likely to become detached. A wheel that is badly distorted, or has an excessively worn spigot mounting, is graded Major.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.

Suspension

One fault: shock absorbers (front), 3.5 times as often as on similar cars.

Shock absorbers (front)

Failed on 185 first tests3.5 times as often as similar carsLikely evidence

What it means

Slight seepage that leaves a film of fluid on a shock absorber does not fail it. Severe leakage, or damage so that it does not function, is Major. A shock absorber missing or likely to become detached is graded Dangerous, though a missing one is only rejected if shock absorbers were fitted as standard.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.

Tyres

Two wear patterns. The strongest is the tyre tread depth (rear): 3.0 times as often as on similar cars.

Tyre tread depth (rear)

Failed on 388 first tests3.0 times as often as similar carsWear pattern

What it means

Only primary grooves count when tread depth is assessed: those holding the wear indicators, or cut as deep as those when new. Shallower secondary grooves are ignored. Tread depth below the minimum for the vehicle is Dangerous, and so is a pattern not visible over the whole tread, but that second row applies only to vehicles that need the lower minimum.

Tyre condition (rear)

Failed on 650 first tests2.3 times as often as similar carsWear pattern

What it means

Exposed or damaged ply or cords are graded Dangerous. A cut in excess of the requirements and deep enough to reach the ply or cords is Major, and testers may open the cut with a blunt instrument to check its depth. A tyre contacting the vehicle through flexing or suspension movement is not a defect; fouling fails only at the time of test.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.

Advisories

Other things testers noted as worn or close to failing, more often than on similar cars.

An advisory is a note from the tester about something that has not failed yet. It is an early warning, not a fail.

Transmission oil leaks (rear)

Noted on 55 first tests19 times as often as similar carsElevated evidence

Shock absorbers (rear)

Noted on 202 first tests3.9 times as often as similar carsElevated evidence

Data: UK MOT open data, 2025. Counts cover advisories recorded on failed first tests only, compared with cars of the same age and mileage.

MOT pass rates

How first tests ended, and how the pass rates are counted.

Passed first time
86in every 100
Passed on the first test.
Fixed at the station
1in every 100
Failed, then fixed at the test station the same day.
Failed
13in every 100
Did not pass, and were not fixed at the test station.

First-attempt pass 85.6% of 23,137 first tests (2025): only cars that passed first time count. Official-style pass 87.4%: cars fixed at the test station also count as a pass. The 1 fixed and the 13 not fixed make the 14 in every 100 that did not pass first time.

By fuel type

First testsTypical mileagePassed first time, as testedPassed first time, same mileage
Diesel12,71367,802 miles8586
Petrol7,08952,215 miles8786
Hybrid3,33574,652 miles8384

Figures are in every 100 first tests. Cars with more miles usually fail more often, so the same-mileage figure gives every fuel the mileage mix of all the cars in this year.

Same model, other years

Passed first time in every 100, all tested in 2025.

4060801001990199520002005201020152018Older carsNewer cars
4060801001990200020102018Older cars

Newer cars are younger, so look for a jump rather than the climb.

YearPassed first timeFirst tests
198781 in every 100361
198880 in every 100584
198981 in every 100956
199079 in every 1001,211
199180 in every 100694
199275 in every 100443
199372 in every 100444
199471 in every 100439
199567 in every 100698
199668 in every 1001,034
199770 in every 1001,403
199868 in every 1001,807
199969 in every 1002,275
200066 in every 1002,300
200165 in every 1004,303
200266 in every 1006,585
200367 in every 1008,626
200466 in every 1007,975
200566 in every 1009,502
200667 in every 10015,148
200768 in every 10020,883
200868 in every 10018,398
200967 in every 10019,579
201068 in every 10022,182
201169 in every 10024,338
201268 in every 10030,011
201373 in every 10032,095
201476 in every 10030,147
201579 in every 10030,018
201683 in every 10029,997
201784 in every 10029,056
2018 This car86 in every 10023,137
201987 in every 10024,151
202087 in every 10020,095
202187 in every 10023,580
202285 in every 10012,310

If you are buying one

What this year's MOT record means for the decision in front of you.

Mileage matters most on a 2018 BMW 3 Series.

Of 2018 BMW 3 Series vehicles with under 45,000 miles, 91 in every 100 passed their 2025 MOT first time. With 87,000 miles or more, 82 in every 100 did.

Under 45,0004,548 tests
91
45,000–58,0004,715 tests
87
58,000–70,000 Typical car4,511 tests
85
70,000–87,0004,675 tests
84
87,000 and over4,680 tests
82

What to check at your mileage

How often each fault turned up on a failed first test, by the car's mileage. Read it as: what is likely to need looking at on a car like the one in front of you.

Under 45,00058,000–70,00087,000 and over
Tyre condition (rear)2.32.83.3
Tyre tread depth (rear)0.51.62.9
Brake pads (rear)0.81.11.7
Shock absorbers (front)0.20.71.6
Petrol engine warning light0.30.51.3

Faults per 100 first tests, by the car's mileage at the test.


When a car fails

60in every 100

of failed cars had one item to fix.

14in every 100

of failed cars had three or more items to fix.

7in every 100

of all first tests had a defect the tester marked dangerous (unsafe to drive away).


Every figure here is a first-attempt MOT rate from DVSA open data for this model line, for cars of this model year tested in 2025. Each mileage band holds a fifth of the tests. MOTs do not test engine or gearbox internals, so this is a pre-purchase checklist, not a full reliability score.

FAQs

Short answers about how to read this model-year guide.

The 2018 BMW 3 Series follows the pattern of the model years either side. Its main cause of failure was Tyre condition (rear), about 19 in every 100 failed tests. In 2025, 85.6% of 23,137 first MOTs on the 2018 BMW 3 Series passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 87.4%. Among 3,337 failed first-attempt MOT tests (test year 2025), Wheel condition (rear) appears more often than on similar cars (2.4% of those tests; 81 observed failures; about 11× more often than similar cars). There is no single reliability score here; this is a pre-purchase checklist built from DVSA open data, not a guarantee for any individual car.
Ranked by how often they were actually recorded, the items that most often failed a 2018 BMW 3 Series at the first attempt were Tyre condition (rear) (19.5%), Tyre tread depth (rear) (11.6%) and Brake pads (rear) (9.0%), each as a share of the year's failed first attempts. That is what goes wrong most often on the car. The common faults table shows a different measure: faults that are unusual compared with similar cars.
Among failed first-attempt tests we highlight patterns that appear more often than on similar cars. Top example: Wheel condition (rear) (2.4% of those tests; 81 observed failures; about 11× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Wheel condition (rear) shows up more often than on similar cars (2.4% of those tests; 81 observed failures; about 11× more often than similar cars). That does not prove a design fault. Age, mileage, and how the car was used still matter. Treat it as a pre-purchase checkpoint, not a manufacturer service bulletin.
Common MOT problem areas for the 2018 BMW 3 Series include Wheel condition (rear), Shock absorbers (front). These are the faults that stand out compared with similar cars, not a complete list of what can go wrong on any individual car.
Advisories flag issues noted at the test and are not a fail rate. We show advisory patterns that appear more often than on similar cars among failed first-attempt tests, separate from common failure rows. Use them as early-warning checks, not as a pass/fail score.
This page highlights MOT failure patterns for the 2018 BMW 3 Series (registration year) using UK DVSA open data for the selected test year. Patterns are compared with cars of a similar age and mileage. It is a buyer checklist from MOT defect statistics, not a full service history or manufacturer service-bulletin list.
No. MOT tests do not cover engine internals, gearboxes, or many electronic modules. Patterns here come from MOT defect statistics only and should not be read as engine or gearbox reliability scores.

About this data

How this page is built and what it can (and can't) say.

These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars, not a full reliability score, and not a pass/fail verdict on any individual vehicle.

2024 2025

What we include

UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.

Same-day repairs

PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.

How we compare

We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.

What this does not cover

  • MOTs do not cover engine internals, gearboxes, or many electronics; this is not a full reliability score.
  • Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
  • Age and mileage matching reduces, but does not remove, differences in how cars were used and maintained.
  • If the data for a car is too thin to say anything useful, we say so rather than guess.

Contains public sector information licensed under the Open Government Licence v3.0.

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