Performance by cohort

3 year bands · 493,319 tests

Pass rate climbs 15.7 points across the cohorts — newer A Class examples clear the test more reliably than the early cars.

Pre-2018 cohort 422,367

Pass

79.6%

Fail

16.1%

PRS

3.9%

Avg mileage at test

73,922 mi

2018–2020 cohort 70,719

Pass

87.7%

Fail

9.6%

PRS

2.2%

Avg mileage at test

46,578 mi

2021+ cohort 233

Pass

95.3%

Fail

3.9%

PRS

0.0%

Avg mileage at test

21,381 mi

Cohort = vehicle's first-registration year band. Same model, different generations of build.

The picture

79.13% pass rate hides a tyre and spring story

Tyre tread depth is the A-Class's most common MOT failure — unusual for a car that averages only 64,079 miles at test time. Spring fractures and windscreen damage follow. At 79.13% across 293,073 tests, the A-Class is one of the better performers in the compact premium class, though that pass rate depends heavily on owners keeping up with tyres they often ignore on a prestige car.

Owner reports paint a different picture of day-to-day reliability. Speed Limit Assist faults, driver display failures within days of delivery, and repeated black screens on the instrument cluster all feature. One dealer kept a car for three weeks chasing an MBUX software issue. None of that fails an MOT — but an underpressure tyre or a stone chip across the A-pillar sightline will. Check the rubber, check the glass, inspect the springs. The A-Class passes when its owner pays attention.

ABI Insurance Group

Group 20–36

Above average — worth comparing quotes before buying. Lower groups cost less to insure; UK fleet average is around Group 22.

Source: ABI Group Rating Panel · administered by Thatcham Research · groups cover standard variants; performance trims may sit higher. Browse all insurance groups →

20–36

out of 50

Compare quotes →

Top ten reasons for rejection.

Filter failures:

Hide wear items to see the model's real defects.

01

Tyre tread depth not in accordance with the requirements

9,306 occurrences · 1.9% of tests
02

Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view

8,755 occurrences · 1.8% of tests
03

A spring or spring component fractured or seriously weakened

8,659 occurrences · 1.8% of tests
04

A suspension joint dust cover severely deteriorated

7,043 occurrences · 1.4% of tests
05

a brake lining or pad worn below 1.5mm

6,452 occurrences · 1.3% of tests
06

A tyre seriously damaged

5,209 occurrences · 1.1% of tests
07

A suspension joint dust cover missing or no longer prevents the ingress of dirt etc

5,185 occurrences · 1.1% of tests
08

A tyre cords visible or damaged

5,068 occurrences · 1.0% of tests
09

A transmission shaft constant velocity joint boot severely deteriorated

4,821 occurrences · 1.0% of tests
10

Wiper blade defective

4,404 occurrences · 0.9% of tests

Counts cover Major and Dangerous defects logged at test. Advisory items excluded so this shows why a car was rejected, not just what the tester flagged in passing.

Worst-case fix budget · top 4 failures

£300–£735

If every one of this A Class's most-logged Major fails hit at the same MOT, that's the real-world UK garage range. Reality is usually one or two items, not all of them. Open the estimator →

Try the calculator

Build your own retest budget.

Year-band analysis

Best year to buy. Worst to avoid.

First-time MOT pass rate split by registration band. A 15.7-point gap between bands means the year you buy Mercedes Benz A Class has a real effect on what turns up at the garage.

Best band to buy

95.3%

2021+ registration

the 2021-on band climbs to 95.3% — a 15.7-point improvement. Tests in this band average 21,381 miles — roughly 53K miles fewer on the clock than the older band. Failures here are mostly wear items: blade defective, not working — the structural issues that drag down older examples don't appear in the top-10 for this band. Post-2020 examples are early in their MOT life and generally show the cleanest records.

Band to be cautious about

79.6%

Pre-2018 registration

On the older band (pre-2018), the data shows a 79.6% pass rate against a fleet average of 95.3% on the newer band. The main culprits logged at test: fractured or broken, tread depth below requirements of 1.6mm, and damaged but not adversely affecting driver's view. Average mileage on test for this band is 73,922 miles — high-mileage wear items are a recurring theme.

Best band to buy: 2021+ (95.3% first-time pass). Worst band to avoid: pre-2018 (79.6% pass). That's a 15.7-point spread across 422,367 older tests and 233 newer ones — year of build makes a material difference on this model.

Year-spread leaderboard →

Tools that pre-empt a retest.

Picked against this car's top failure patterns. Affiliate links to Amazon UK — we earn a small cut at no cost to you. Disclosed up-front, doesn't shape the data.

Item 01 · Amazon UK

Digital tyre-tread depth gauge

Five quid for a gauge beats £150 for a retest. UK MOT minimum is 1.6mm — most testers fail anything below 2mm to be safe.

Search Amazon UK

Item 02 · Amazon UK

Brake pad measurement gauge

Testers fail pads under 1.5mm. A wear gauge tells you if you've got two months left or two weeks.

Search Amazon UK

My Motor World · affiliate

Parts & supplies for this fix

Affiliate links — small commission, no extra cost to you.

Denso

Denso W14E Spark Plug (Single)

£1.09

View at My Motor World →

Denso

Denso W16EX-U Spark Plug (Single)

£1.09

View at My Motor World →

Denso

Denso W16FSR Spark Plug (Single)

£1.09

View at My Motor World →

Denso

Denso W9LM-US Spark Plug (Single)

£1.09

View at My Motor World →

Click Mechanic · affiliate

Book a mobile mechanic

Affiliate links — small commission, no extra cost to you.

Mobile mechanic · UK-wide

Book a mechanic at your door.

Fixed-price quotes upfront. No garage needed. Click Mechanic sends a vetted local mechanic to you — home, work, or roadside.

Get a quote →

Owner reports · Honest John

What owners actually report.

Verbatim faults logged by owners on honestjohn.co.uk over recent years. We didn't summarise — these are the words people typed in.

What's good

Innovative infotainment system that looks great. Interior looks pretty swish. Comfortable and easy to drive.

Recent owner-reported faults

5 Apr 2020
Reports of issues with reader's Mercedes-Benz A-Class. Dealer's had the car for three weeks: 1. Speed Limit Assist feature not working correctly. This feature is designed to keep the driver informed of the prevailing speed limit at all times. The fault manifests itself in a number of different ways but one simple example is driving past a de-restriction sign will sometimes correctly show the 60mph limit symbol on the dash until the next speed limit sign or on other occasions it will show a de-restriction symbol for 10 seconds followed by no symbol. 2. Active Lane Assist, designed to sense when the vehicle is unintentionally crossing a white line and applying the brakes on one side to keep the vehicle in lane, however, this frequently senses things other than white lines. These might be lines of shiny bitumen, rivulets of water or boxes around bus stops which means that when it senses these the brakes are incorrectly applied which can be dangerous. 3. New problem introduced by software update FU2/063, Personal POI's do not give Visual or Audible Warnings. This worked correctly on the previous release of software. 4. Easy Entry/Exit, seat not working correctly. This feature is intended to position the drivers seat for Easy Entry/Exit then move it to the driving position when the ignition is switched on. Intermittent problem where when entering the car and switching the ignition on the seat briefly moves backwards and then returns to the Easy Entry/Exit position. 5. Top LED dash strip not as bright as other LED strips. The strip has been replaced twice and is now better than it was originally. The dealer agrees that this is not correct but has no solution. 6. When turning at low speed proximity sensors report non-existent hazards. Turning right off a main road, if a vehicle has just passed on the right the proximity alarm will sound continually as you start to turn despite the passing vehicle having already gone past, indeed the alarm seems to be locked on for about 5 seconds. This is exceedingly distracting and therefore dangerous but Mercedes have no solution. 7. A plastic rather than metallic rattle from somewhere at the back of the car. Several attempts have been made to correct this without success.
3 Oct 2019
Report of failure of driver display on new 2019/69 Merceded Benz A 220 AMG Premium Plus a couple of days after purchase.
30 Aug 2019
Report of repeated failure of driver instrument display of 2019 Mercedes-Benz A250 bought as an ex-demonstrator at 3,500 miles in June 2019. Frequently it does not switch on leaving a black screen in front of the driver with no means of viewing the speedo, petrol guage, or ensuring the transmission is in reverse, drive or park.

Source: honestjohn.co.uk · 3 reports indexed

Recall history

49 UK recalls on record.

The A Class has 49 official UK vehicle recalls covering defect details, remedies, and affected build dates.

See all recalls

Buying or keeping an A Class?

Use the failure ranking as a pre-test checklist or a haggling lever. Treat the headline pass rate as a fleet-wide trend, not a guarantee on any individual car.

If you own an A Class and your last MOT looked nothing like the ranked failures above, that's normal — individual cars vary widely. The ranking shows the patterns testers flag most often across the country.