Smart Forfour: what fails at MOT
32,000 MOT tests on the Smart Forfour in 2024, counted. 25.6% failed at the first attempt.
The short answer
25.4% of Smart Forfour tests failed at the first attempt. Cars of the same ages averaged 20.6%, so the Forfour does worse than most cars its age.
It fails most often on tyres (5.6% of tests), lights and electrics (4.9% of tests) and suspension (4.4% of tests). It fails on tyres, wipers, washers and windscreen and exhaust and emissions more often than most cars its age.
By year of registration
Older cars fail more, whatever the model. So each year is shown beside the figure for all cars first used that year.
| First used | Tests | Failed first time | All cars that year | Typical mileage |
|---|---|---|---|---|
| 2019 | 2,706 | 17.5% | 13.4% | 22,600 14,800 to 34,000 |
| 2018 | 5,590 | 18.0% | 15.6% | 29,400 19,900 to 41,300 |
| 2017 | 6,794 | 22.4% | 18.2% | 35,900 24,700 to 49,300 |
| 2016 | 7,377 | 27.2% | 21.3% | 42,000 30,200 to 56,000 |
| 2015 | 7,611 | 31.3% | 24.4% | 48,400 36,500 to 62,400 |
| 2006 | 558 | 44.6% | 42.4% | 96,100 74,100 to 122,000 |
| 2005 | 760 | 42.6% | 42.2% | 99,400 76,100 to 126,000 |
Green is at least three points better than other cars that year, red at least three points worse. Typical mileage is the middle reading at the test, with the range the middle half of cars fell in.
Where it fails
The share of Smart Forfour tests with at least one failure in each part of the MOT, beside what cars of the same ages average.
| Part of the test | Forfour | Cars its age | |
|---|---|---|---|
| Tyres | 5.6% | 4.0% | More than most |
| Lights and electrics | 4.9% | 4.4% | |
| Suspension | 4.4% | 3.5% | |
| Wipers, washers and windscreen | 4.0% | 2.3% | More than most |
| Exhaust and emissions | 3.4% | 1.3% | More than most |
| Brakes | 2.6% | 3.1% | |
| Body and structure | 1.4% | 1.1% | |
| Steering | 0.5% | 0.8% |
The parts that fail most
- Tyre2.9%
- Tyre tread2.5%
- Ball joint2.5%
- Wipers2.2%
- Exhaust emissions2.1%
- Brake light2.1%
- Washers1.8%
- Headlamp aim1.6%
- Brake pads1.3%
- Engine warning light1.1%
Share of tests with a failure on that part.
The most common failures
- Tyre tread: below requirements of 1.6mm2.4%
- Ball joint: excessively worn2.3%
- Wipers: does not clear the windscreen effectively2.2%
- Brake light: not working2.0%
- Exhaust emissions: Lambda reading after 2nd fast idle outside specified limits1.8%
- Washers: provides insufficient washer liquid1.4%
- Brake pads: less than 1.5 mm thick1.3%
- Tyre: has ply or cords exposed1.2%
- Engine warning light: inoperative or indicates a malfunction1.1%
- Tyre: has a cut in excess of the requirements deep enough to reach the ply or cords0.9%
What testers warn about
Advisories are things that passed this time but are wearing. They are the best guide to next year's bills.
- Tyre tread: worn close to legal limit/worn on edge13.8%
- Brake discs: worn, pitted or scored, but not seriously weakened7.2%
- Tyre: slightly damaged/cracking or perishing7.0%
- Brake pads: wearing thin4.0%
- Brake discs: worn, but not excessively2.8%
- Suspension pins and bushes: pin or bush worn but not resulting in excessive movement1.5%
- Ball joint: has slight play1.2%
- Child Seat fitted not allowing full inspection of adult belt1.1%
What these figures can't tell you
An MOT is a safety and emissions test. These figures show how often the model fails that test. They say nothing about engines, gearboxes or electronics that break between tests, and how a car has been looked after matters more than its badge. The car you are looking at has its own MOT record, and that is the one to read.
Ask before you travel
- “How much tread is left on each tyre, and how old are they?”
- “Do the wipers and washers work properly, and is the windscreen chipped or cracked?”
- “Has it ever failed on emissions or an exhaust leak, and what was done about it?”
- “Do all the lights work, including the number plate lights and brake lights?”
Check a Smart Forfour's own MOT record
Type the registration from the advert. You'll see every test that car has had, what it failed on and what it was warned about, free.
Where this comes from
DVSA anonymised MOT tests and results, 2024, published by the Driver and Vehicle Standards Agency. Contains public sector information licensed under the Open Government Licence v3.0. The counting is Hindsight's own.
First-attempt MOT tests of cars first used 2004 to 2021. A test counts as failed if it failed or only passed after a repair during the test. Retests are left out. Built on 13 November 2026.