Smart Forfour MOT pass rate and common problems
79.6% of 33,784 Smart Forfour MOT tests pass.
The Forfour's pass rate of 79.6% is in line with the average across all Smart models, at 79.0%.
The Smart Forfour's pass rate of 79.6% is in line with the national average for cars, at 79.2%.
Own this Smart Forfour?
This is the average across every Smart Forfour in the dataset. Look up your own registration for its actual MOT history, and a free place to keep its maintenance records.
Have service invoices? Upload and keep them with your car’s history →
How to check and keep your Smart’s service history →
Pass rate by vehicle age
Pass rate drops sharply with age: the Smart Forfour tested at 3–6 years pass 87.0% of the time, compared with just 65.5% at 15+ years.
| Vehicle age | Pass rate | Tests | Average mileage |
|---|---|---|---|
| 0–3 years | no tests recorded | 0 | no reading |
| 3–6 years | 87.0% | 6,213 | 28,014 miles |
| 6–10 years | 79.2% | 24,957 | 43,904 miles |
| 10–15 years | too few tests (24) | 24 | no reading |
| 15+ years | 65.5% | 2,590 | 100,551 miles |
Common MOT failure reasons for the Smart Forfour
The most common reason the Smart Forfour fails its MOT is lamps, reflectors and electrical equipment — present in 35.5% of failed tests, most often logged as "Not working".
| Category | Share of failed tests | Example |
|---|---|---|
| Lamps, reflectors and electrical equipment | 35.5% | Not working |
| Tyres | 33.0% | Tread depth below requirements of 1.6mm |
| Suspension | 26.0% | Ball joint excessively worn |
| Visibility | 21.0% | Does not clear the windscreen effectively |
| Noise, emissions and leaks | 19.5% | Lambda reading after 2nd fast idle outside specified limits |
| Brakes | 16.7% | Less than 1.5 mm thick |
| Body, chassis, structure | 7.5% | Has a major leak of exhaust gases |
| Steering | 2.9% | Ball joint has excessive play |
| Identification of the vehicle | 1.2% | Does not conform to the specified requirements |
| Seat belts and supplementary restraint systems | 1.1% | Warning lamp indicates a fault |
Buying a used Smart Forfour: what to check
These checks follow the Smart Forfour’s own MOT record: the areas it fails on most often, and how that changes as the car gets older. None of them replaces a mechanic’s inspection, but they tell you where to look first.
The biggest drop in pass rate for the Smart Forfour comes between 6–10 years and 15+ years old, from 79.2% to 65.5%. If you are looking at one in or just past that range, read its MOT history closely.
By mileage, the steepest fall is from 30,000–60,000 mi to 60,000–90,000 mi: 79.7% down to 67.7%. Mileage matters as well as age, so compare the car’s recorded mileages with its year.
1. Lights and electrics
Recorded in 35.5% of failed Smart Forfour MOTs. 44.9% of tests at 15+ years failed on lights and electrics, against 3.4% at 3–6 years.
Walk round with the lights on: headlights (dipped and main), indicators, brake lights, fog light and number-plate lamp. Check the dashboard warning lights come on with the ignition, then go out once the engine starts.
2. Tyres
Recorded in 33.0% of failed Smart Forfour MOTs.
Check tread depth across the whole width of every tyre, including the inner edge. Uneven wear can point to alignment or suspension problems. Look for cuts and bulges in the sidewalls.
3. Suspension
Recorded in 26.0% of failed Smart Forfour MOTs. 16.8% of tests at 15+ years failed on suspension, against 1.7% at 3–6 years.
Listen for knocks over bumps and speed humps, and check the car sits level. Push down on each corner: it should settle rather than keep bouncing.
4. Windscreen and wipers
Recorded in 21.0% of failed Smart Forfour MOTs.
Look for windscreen chips and cracks in the driver’s line of sight, and check the wipers clear the screen and the washers work.
5. Exhaust, emissions and leaks
Recorded in 19.5% of failed Smart Forfour MOTs. 7.5% of tests at 15+ years failed on exhaust, emissions and leaks, against 1.1% at 3–6 years.
Look under the car for fresh oil or coolant, and listen for blows or rattles from the exhaust. Watch for smoke from the tailpipe when the engine starts and when you accelerate.
Check the car’s own MOT history. Averages describe the model, not the car in front of you. Look up its registration for past failures, advisories that were never fixed, and gaps or dips in the recorded mileage.
Ask for the service history. Invoices show what was done and when; a stamp alone shows less. See how to check Smart service history and what a service history check can tell you.
Related Smart models
- Smart Fortwo — 84.8% pass rate
- Smart Fortwo Coupe — 72.9% pass rate
- Smart City Coupe — 68.4% pass rate
- Smart Fortwo Cabriolet — 74.9% pass rate
- Smart Roadster 80 Auto(rhd) — 74.4% pass rate
- Smart Cabriolet — 71.2% pass rate
Frequently asked questions
- What is the MOT pass rate for the Smart Forfour?
- 79.6% of Smart Forfour MOT tests pass, based on 33,784 tests in the DVSA anonymised MOT tests and results dataset.
- What are the most common MOT failures for the Smart Forfour?
- The most common reason the Smart Forfour fails its MOT is lamps, reflectors and electrical equipment — present in 35.5% of failed tests, most often logged as "Not working".
- What are the common problems with the Smart Forfour?
- Going by its MOT results, the most common problem areas on the Smart Forfour are lights and electrics; tyres; suspension. 44.9% of tests at 15+ years failed on lights and electrics, against 3.4% at 3–6 years.
- What should I check when buying a used Smart Forfour?
- Start with the areas it most often fails its MOT on: lights and electrics; tyres; suspension; windscreen and wipers; exhaust, emissions and leaks. Then check the specific car's MOT history by registration for failures, advisories and mileage, and ask the seller for service invoices.
- Does this show the Smart Forfour's service history?
- No — this is MOT test data, which covers roadworthiness, not servicing. A service history is a separate record of maintenance work, which a specific car only has if its owner has kept it. See the Smart service history guide for how to check and keep one.