Common problems

Smart Forfour (before 2014) common problems

What MOT testers find on the Smart Forfour (before 2014): the parts that fail or get advisories most often at each age, against all cars of the same age. From 10,940 DVSA MOT tests taken 2022 to 2025. These figures cover cars first used before 2014. Later cars sold under the same name are not included; see Smart Forfour cars first used 2014 or later.

MOT data updated 28 September 2026

At 18 years, the most tested age

Lights and electrics fails per 100 MOTs (n=2,974)27.0

All cars at 18 years (n=3,261,622)21.4

Suspension advisories and minor defects per 100 MOTs (n=2,974)34.4

All cars, same age (n=3,261,622)35.3

What stands out

Lights and electrics fails show up on 27.0 of every 100 MOTs of a Smart Forfour (before 2014) at 18 years old (n=2,974), against 21.4 for all cars of that age (n=3,261,622).
Suspension fails are less common: 12.6 per 100 MOTs against 17.2 for all cars at the same age.
The fail item testers record most often at 18 years: headlamp aim: projected beam image is obviously incorrect, on 7.6 per 100 MOTs (all cars 4.0).
The most common advisory or minor defect: brake discs: worn, pitted or scored, but not seriously weakened, on 14.5 per 100 MOTs.

Problems by part at 18 years

How many of every 100 MOTs found a fail, or an advisory or minor defect, in each area. A test with faults in two areas counts in both.

Smart Forfour (before 2014) at 18 years (n=2,974) against all cars at 18 years (n=3,261,622). Per 100 MOTs.
Area	Fails	All cars	Advisories	All cars
Lights and electrics	27.0	21.4	27.4	17.8
Brakes	12.7	12.9	29.2	32.3
Suspension	12.6	17.2	34.4	35.3
Body and structure	9.0	8.7	10.4	14.7
Windscreen, wipers and mirrors	7.7	7.3	7.2	6.2
Tyres	6.0	7.0	26.8	27.6
Steering	5.3	3.9	7.4	5.6
Exhaust, emissions and leaks	5.1	6.8	6.2	14.1
Seat belts and airbags	2.1	2.7	1.0	1.3
Number plates and VIN	1.1	0.6	8.2	5.5
Road wheels	0.4	0.5	2.8	1.3

What testers fail most on the Forfour (before 2014) at 18 years

Fail items on the Smart Forfour (before 2014) at 18 years (n=2,974), per 100 MOTs, with all cars at the same age (n=3,261,622).
Item	Area	Per 100 MOTs	All cars	Typical repair (estimate)
Headlamp aim: projected beam image is obviously incorrect	Lights and electrics	7.6	4.0	£16 to £39 per car (rough guide)
Side/position light not working	Lights and electrics	5.3	5.6	£10 to £47 per lamp
Wipers not clearing screen	Windscreen, wipers and mirrors	4.5	3.0	£15 to £30 per blade
Brake light not working	Lights and electrics	4.5	4.0	£10 to £47 per lamp
Handbrake too weak	Brakes	3.8	2.8
Steering track rod end: ball joint play	Steering	3.4	2.0	£54 to £128 per side (rough guide)
Dipped headlight not working	Lights and electrics	3.4	2.1	£18 to £86 per lamp
Coil spring broken	Suspension	3.4	3.1	£64 to £236 per spring (rough guide)
Driveshaft CV boot split	Body and structure	2.9	3.2	£88 to £196 per boot (rough guide)
Brake pads under 1.5 mm	Brakes	2.8	1.8	£72 to £174 per axle (rough guide)

Early warnings: advisories and minor defects at 18 years

Advisories and minor defects are recorded, but the car still passes. Across all cars, a part with an advisory or minor defect failed at the next MOT 5.5 times in 100 (n=88,666,940 pairs of consecutive MOTs), against 0.3 times in 100 when the same part had none (n=12,936,860,350).

Advisories and minor defects on the Smart Forfour (before 2014) at 18 years (n=2,974), per 100 MOTs, with all cars at the same age (n=3,261,622).
Item	Area	Per 100 MOTs	All cars	If it needs replacing (estimate)
Brake discs: worn, pitted or scored, but not seriously weakened	Brakes	14.5	11.1	£148 to £376 per axle (rough guide)
Tyre condition: slightly damaged/cracking or perishing	Tyres	13.6	9.8	£88 to £145 per tyre
Tread depth: worn close to legal limit/worn on edge	Tyres	13.3	17.4	£88 to £145 per tyre
Coil spring: corroded	Suspension	13.2	7.7
Brake pads: wearing thin	Brakes	8.7	6.4	£72 to £174 per axle (rough guide)
Registration plate lamp(s): inoperative in the case of multiple lamps or light sources	Lights and electrics	8.7	5.8
Registration plates: deteriorated but not likely to be misread	Number plates and VIN	8.2	5.4	£23 to £63 per plate (rough guide)
Headlamp: lens slightly defective	Lights and electrics	7.7	4.2
Headlamp: has a product on the lens but not seriously reducing light output	Lights and electrics	6.9	3.8	£28 to £98 per lamp (rough guide)
Linkage ball joints: ball joint has slight play	Suspension	6.1	2.7	£33 to £102 per link (rough guide)

Repair estimates are a guide for an independent garage: labour at the national median local garage rate (median £78 an hour from 65 garages, ONS price quotes) times estimated labour hours, plus a parts band. Labour hours and most parts bands are estimates, not quotes, and prices vary by model, engine and region. A warning light fault shows the cost of the diagnosis only.

How problems change with age

Fails per 100 MOTs in the three most common areas at 18 years. Ages with fewer than 1,000 tests are not shown.
Age	Tests (n)	Lights and electrics	Brakes	Suspension
16 years	1,536	24.6	10.6	10.2
17 years	2,914	26.2	11.6	12.5
18 years	2,974	27.0	12.7	12.6
19 years	2,333	27.1	12.0	12.0
20 years	1,183	24.4	11.2	12.0

What to check on a viewing

On the Smart Forfour (before 2014), testers most often record headlamp aim: projected beam image is obviously incorrect; side/position light not working; wipers not clearing screen. Look at these first, then the areas below.

Lights and electrics

With someone outside, try every light: dipped and main beam, indicators, brake lights, fog lights and number plate lamps.
Check that the warning lights come on with the ignition and go out once the engine runs.
Look for misted, cracked or yellowed headlamp lenses.

Brakes

On the test drive the car should stop in a straight line without pulling, juddering or grinding.
Look at the discs through the wheels for a deep lip, heavy rust or scoring.
Check that the handbrake or electronic parking brake holds the car on a slope.
Ask when the pads, discs and brake fluid were last changed, and for the receipts.

Suspension

Listen for knocks or clonks over speed bumps and rough roads on the test drive.
Push down hard on each corner: the car should settle at once rather than keep bouncing.
Look behind the wheels for broken or heavily rusted coil springs and split rubber bushes.
Check that the car sits level and that no tyre is worn on one edge only.

Ask for the car's MOT history and service record: advisories that repeat from one year to the next show what has been left. GOV.UK MOT history.

Questions

What are the most common problems on the Smart Forfour (before 2014)?

At 18 years, the age with the most MOT tests (2,974), the fail items testers record most often on the Smart Forfour (before 2014) are headlamp aim: projected beam image is obviously incorrect (7.6 per 100 MOTs), side/position light not working (5.3 per 100 MOTs), wipers not clearing screen (4.5 per 100 MOTs). The most common advisories or minor defects are brake discs: worn, pitted or scored, but not seriously weakened (14.5) and tyre condition: slightly damaged/cracking or perishing (13.6).

Which parts of the Smart Forfour (before 2014) fail more often than on other cars?

At 18 years: lights and electrics (27.0 per 100 MOTs against 21.4 for all cars); steering (5.3 per 100 MOTs against 3.9 for all cars). Compared with 3,261,622 MOTs of all cars the same age.

Smart Forfour (before 2014) problems by area

Other Smart models

All Smart models · Common problems by make

Read this with care. A fail rate is not a measure of build quality. How far cars are driven, how they are used and how well owners maintain them all change it, and wear items such as tyres and brake pads are common fails. Compare a model only with cars of the same age. Methodology and limits.

The all cars figures cover all class 4 vehicles (cars and light vans) tested at the same age.

Looking at a Smart Forfour (before 2014)?

These figures describe the model, not the car in front of you. Found one you might buy? See what the VetTheCar Buying Report covers, or use the tools that work without a registration.

See a sample report Car tools · MOT fail rates by model · Compare models by MOT record

Repair estimates: ONS consumer price quotes for local garage labour (09/2025 to 08/2026), the MOT inspection manual for defect wording, and estimated labour hours and parts bands. Not affiliated with or endorsed by ONS.

Source

Contains public sector information licensed under the Open Government Licence v3.0. Source: DVSA anonymised MOT test data, class 4 normal MOT tests, 2022 to 2025. MOT data updated 28 September 2026.

Not affiliated with or endorsed by DVSA. How we calculate these figures · Data sources