How reliable is the Smart Forfour compared with other cars?

We do not publish a comparison for the Smart Forfour, because the cars of this model that have been tested do not cover a wide enough range of ages and mileages. Its raw pass rate is 53.5% across 620 tests, but comparing a raw rate between models mostly ranks them by how new they are rather than how good they are. The failure and advisory patterns further down the page are still drawn from real tests and are worth reading.

What is the most common MOT failure on a Smart Forfour?

The item recorded most often is "The aim of a headlamp is not within limits laid down in the requirements", which appears in 32.3% of failed Smart Forfour tests. Because one failed test can list several items, these shares do not add up to 100%.

What do testers most often warn about on a Smart Forfour?

The most common advisory is "A spring or spring component fractured or seriously weakened", noted on 21.8% of all Smart Forfour tests. An advisory is not a failure: it flags something that will likely need attention before the next test.

What mileage does a Smart Forfour usually have at its MOT?

The average odometer reading recorded at test is 98,227 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.

Model reliability file

Smart Forfour MOT pass rate & common failures

From 620 recorded MOT tests of the Smart Forfour, published by DVSA.

Data updated 29 July 2026

Quick answer

Across 620 MOT tests, 53.5% of Smart Forfour tests ended in a pass. This figure is not adjusted for age or mileage, so it is not a reliability ranking: the Smart Forfour fleet does not yet cover a wide enough spread of ages and distances to compare it fairly against other models. Its most commonly recorded failure is aim of a headlamp is not within limits laid down in the requirements, which appears in 32.3% of failed tests. Cars of this model average 98,227 miles on the odometer when tested.

At a glance

Recorded pass rate

53.5%unadjusted, not comparable620 tests

We are not publishing a ranking for the Forfour. The examples tested do not cover a wide enough spread of ages and mileages to compare it fairly, and an unadjusted pass rate mostly sorts models by how recently they were bought rather than how well they were built. The failure and advisory patterns below come from the same 620 tests and are worth reading on their own terms.

DVSA recorded wording

Most common failure items

Share of failed Smart Forfour tests in which each item was recorded. One failed test often lists several items, so these do not sum to 100%.

1.The aim of a headlamp is not within limits laid down in the requirements32.3%
71 occurrencesHeadlamp aim incorrect explained
2.Wiper blade missing or obviously not clearing the windscreen13.6%
30 occurrencesWiper or washer not working properly explained
3.Product on the lens or light source which obviously reduces light intensity or changes emitted colour to other than white or yellow13.2%
29 occurrencesLamp of the wrong colour, position or intensity explained
4.A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning12.3%
27 occurrencesLamp not working explained
5.Parking brake efficiency below minimum requirement10.9%
24 occurrencesParking brake efficiency too low explained
6.Headlamp reflector or lens seriously defective or missing10.9%
24 occurrences
7.A steering ball joint with excessive wear or free play10.0%
22 occurrencesBall joint worn explained
8.A suspension joint dust cover missing or no longer prevents the ingress of dirt etc8.6%
19 occurrencesSuspension joint dust cover missing or split explained
9.A spring or spring component fractured or seriously weakened8.6%
19 occurrencesRoad spring broken or fractured explained
10.A brake lining or pad worn below 1.5mm8.6%
19 occurrencesBrake drum or shoe worn or contaminated explained

Warnings without a failure

Most common advisories

Share of all Smart Forfour tests carrying each advisory. The denominator differs from the failure list above because an advisory can be issued on a car that passed.

1.A spring or spring component fractured or seriously weakened21.8%
134 testsRoad spring broken or fractured explained
2.Brake disc or drum excessively weakened, insecure or fractured20.5%
126 testsBrake disc worn, pitted or scored explained
3.A tyre seriously damaged20.1%
124 testsTyre damaged or deteriorated explained
4.Tyre tread depth not in accordance with the requirements18.8%
116 testsTyre worn close to the legal limit explained
5.A brake lining or pad worn below 1.5mm10.2%
63 testsBrake drum or shoe worn or contaminated explained
6.Number plate inscription missing or illegible8.1%
50 testsRegistration plate missing, insecure or illegible explained
7.A suspension pin, bush or joint excessively worn7.6%
47 testsSuspension arm bush worn explained
8.A shock absorber damaged to the extent that it does not function or showing signs of severe leakage6.2%
38 testsShock absorber defective explained

The rest of the record

Everything else recorded on the Smart Forfour

The 16 other defects testers recorded on this model, beyond the most common listed above. Each links to what it means and what it takes to put right.

What gets tested

The Forfour fleet

Average mileage recorded at test: 98,227
Fuel mix of tested cars: Petrol99.7%

Trim names grouped into this model (6)

Recorded exactly as DVSA holds them. Trim-level names are rolled up so one model is not split across a dozen thin pages.

FORFOUR BLACK EDITION
FORFOUR PASSION
FORFOUR PASSION SEMI-AUTO
FORFOUR PULSE
FORFOUR PULSE SEMI-AUTO
FORFOUR PURE

Check a specific Smart Forfour

A model average tells you the pattern. Its own MOT record tells you the car.

Compare within the range

Other Smart models

Smart Fortwo — 68.1% unadjusted
Smart EQ Forfour — 85.3% unadjusted
Smart EQ Fortwo — 91.8% unadjusted
Smart Roadster — 68.8% unadjusted
All Smart models

Common questions

How reliable is the Smart Forfour compared with other cars?: We do not publish a comparison for the Smart Forfour, because the cars of this model that have been tested do not cover a wide enough range of ages and mileages. Its raw pass rate is 53.5% across 620 tests, but comparing a raw rate between models mostly ranks them by how new they are rather than how good they are. The failure and advisory patterns further down the page are still drawn from real tests and are worth reading.
What is the most common MOT failure on a Smart Forfour?: The item recorded most often is "The aim of a headlamp is not within limits laid down in the requirements", which appears in 32.3% of failed Smart Forfour tests. Because one failed test can list several items, these shares do not add up to 100%.
What do testers most often warn about on a Smart Forfour?: The most common advisory is "A spring or spring component fractured or seriously weakened", noted on 21.8% of all Smart Forfour tests. An advisory is not a failure: it flags something that will likely need attention before the next test.
What mileage does a Smart Forfour usually have at its MOT?: The average odometer reading recorded at test is 98,227 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.

How this was worked out

Method and limits

Figures come from the DVSA anonymised MOT testing dataset, published under the Open Government Licence. Only class 4 initial tests are counted: retests are excluded so a car appears once, and abandoned tests are excluded entirely. No adjusted rate is shown because this model's tested examples do not cover enough of the national age and mileage range for standardisation to mean anything.

An MOT measures whether a car met a legal standard on the day. It is not a breakdown record, a service history or a running-cost estimate, and a pass rate is a property of a fleet rather than a prediction about one car.