Model Reports 4 min read Updated 18 Oct 2026

Mercedes-Benz CLS 2015: reliability & common MOT faults

In 2025, 78 in every 100 first MOTs on a 2015 Mercedes-Benz CLS were passes. Most common reason for a fail: Tyre condition (front).

Summary

The 2015 Mercedes-Benz CLS follows the pattern of the model years either side.

At a glance

How 2,729 first tests went in 2025.

Passed first time
78 in every 100
Did not pass first time
22 in every 100590 failed first-attempt tests
The typical car
10 yearsabout 85,203 miles
First tests counted
2,729

What failed most often

  1. Tyre condition (front)22 in every 100 failed tests
  2. Coil spring (rear)12 in every 100 failed tests
  3. Diesel engine warning light11 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 2015 Mercedes-Benz CLS 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.

Brakes

One fault: handbrake lever, 5.9 times as often as on similar cars.

Figures below are measured across the 588 of 590 failed first attempts (99.7%) 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.

Handbrake lever

Failed on 26 first tests5.9 times as often as similar carsPossible evidence

What it means

A parking brake lever pivot or ratchet mechanism that is obviously worn is graded Minor. It is Major when worn to the extent that the brake may inadvertently release, and also when the ratchet is not holding correctly. A lever must have obvious excessive travel before being rejected.

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

Suspension

Three faults. The strongest is the anti-roll bar ball joint dust cover (front): 4.3 times as often as on similar cars.

Anti-roll bar ball joint dust cover (front)

Failed on 20 first tests4.3 times as often as similar carsPossible evidence

What it means

A missing anti-roll bar ball joint dust cover is Major, and so is one that no longer prevents the ingress of dirt. A cover that is only severely deteriorated is Minor. DVSA uses one wording for the dust cover on any suspension joint.

Anti-roll bar linkage ball joint dust cover (front)

Failed on 45 first tests3.8 times as often as similar carsLikely evidence

What it means

A suspension joint dust cover that is severely deteriorated is Minor. It becomes Major once it is missing or no longer prevents the ingress of dirt, so what matters is whether it still keeps dirt out. DVSA words this for any suspension joint dust cover, and files it here under anti-roll bars.

Coil spring (rear)

Failed on 68 first tests2.1 times as often as similar carsPossible evidence

What it means

A missing bump stop rubber is not a reason to fail a coil spring. When the vehicle is jacked and lowered, a spring that does not correctly locate as the suspension returns to its normal running position is rejected as insecurely attached. A missing spring is Major, and graded Dangerous where directional control is affected.

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

Noise, emissions and leaks

One fault: diesel engine warning light, 3.7 times as often as on similar cars.

Diesel engine warning light

Failed on 65 first tests3.7 times as often as similar carsLikely evidence

What it means

An engine malfunction indicator lamp that is illuminated to show a malfunction is graded Major on a diesel, but only on the diesels the test covers, which depends on the vehicle type and when it was first used. DVSA lists it under exhaust emissions for compression ignition engines, and the detail line for the row also names an inoperative lamp.

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

Tyres

Three wear patterns. The strongest is the tyre condition (front): 3.0 times as often as on similar cars.

Tyre condition (front)

Failed on 131 first tests3.0 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.

Also noted as an advisory

Testers also noted it as an advisory, worn but not yet failing, on 55 first tests, 2.2 times as often as on similar cars.

Tyre tread depth (rear)

Failed on 55 first tests2.9 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 102 first tests2.8 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 count notes recorded on failed first tests only.

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. Advisories for the faults above are shown with those faults.

Wheel bearings (front)

Noted on 43 first tests13 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
78in every 100
Passed on the first test.
Fixed at the station
2in every 100
Failed, then fixed at the test station the same day.
Failed
20in every 100
Did not pass, and were not fixed at the test station.

First-attempt pass 78.4% of 2,729 first tests (2025): only cars that passed first time count. Official-style pass 80.3%: cars fixed at the test station also count as a pass. The 2 fixed and the 20 not fixed make the 22 in every 100 that did not pass first time.

Same model, other years

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

406080100200520102015Older carsNewer cars
40608010020102015Older cars

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

YearPassed first timeFirst tests
200571 in every 100799
200670 in every 1001,098
200767 in every 1001,373
200869 in every 1001,128
200966 in every 100895
201065 in every 100927
201173 in every 1001,026
201274 in every 1001,012
201371 in every 1002,809
201474 in every 1001,644
2015 This car78 in every 1002,729
201679 in every 1002,000
201780 in every 1001,415
201883 in every 100900
201982 in every 1001,002

If you are buying one

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

Mileage makes a modest difference on a 2015 Mercedes-Benz CLS.

Of 2015 Mercedes-Benz CLS vehicles with under 62,000 miles, 79 in every 100 passed their 2025 MOT first time. With 114,000 miles or more, 74 in every 100 did.

Under 62,000556 tests
79
62,000–78,000540 tests
80
78,000–93,000 Typical car534 tests
81
93,000–114,000553 tests
78
114,000 and over543 tests
74

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 62,00078,000–93,000114,000 and over
Tyre condition (front)4.55.25.5
Coil spring (rear)2.92.61.8
Diesel engine warning light2.02.22.6
Tyre tread depth (rear)1.31.13.5

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

When a car fails

47in every 100

of failed cars had one item to fix.

24in every 100

of failed cars had three or more items to fix.

9in 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 2015 Mercedes-Benz CLS follows the pattern of the model years either side. Its main cause of failure was Tyre condition (front), about 22 in every 100 failed tests. In 2025, 78.4% of 2,729 first MOTs on the 2015 Mercedes-Benz CLS passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 80.3%. Among 590 failed first-attempt MOT tests (test year 2025), Handbrake lever appears more often than on similar cars (4.4% of those tests; 26 observed failures; about 5.9× 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 2015 Mercedes-Benz CLS at the first attempt were Tyre condition (front) (22.3%), Coil spring (rear) (11.6%) and Diesel engine warning light (11.1%), 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: Handbrake lever (4.4% of those tests; 26 observed failures; about 5.9× more often than similar cars). These are statistical signals, not a diagnosis of any individual car.
Handbrake lever shows up more often than on similar cars (4.4% of those tests; 26 observed failures; about 5.9× 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 2015 Mercedes-Benz CLS include Handbrake lever, Anti-roll bar ball joint dust cover (front), Anti-roll bar linkage ball joint dust cover (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 2015 Mercedes-Benz CLS (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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