MOT failures by make

Smart MOT faults: which failures are more common than on similar cars

Across 177,310 MOT tests of Smart cars in 2023–2024, 3 of the make's most common failure items stand out against cars of the same age, mileage and fuel, led by “Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits” at 2.22× the comparable rate. Overall Smarts passed 71.6% of tests and failed 1.06× as often as comparable cars.

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Data to 2024-12-30 · Page updated 2026-09-28 · Publisher: 73 Auto

Smart MOT tests: 177,310; 92,281 cars, 2023–2024
Initial pass rate: 71.6%; DVSA results, retests excluded
Faults that stand out: 3; passed the make × item gate

Failures more common on Smarts than on similar cars

Each links to the model-by-model and age breakdown for Smart.

Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits · 2.22× · 1.74% of tests
Service brake performance: excessively binding · 1.71× · 1.32% of tests
Washers: provides insufficient washer liquid · 1.52× · 2.14% of tests

Smart’s most common MOT failure items

Ranked by how many Smart tests failed on each item. The last column compares with cars of the same age, mileage and fuel (1.00 = the same rate).

Smart: most common MOT failure items with observed ÷ expected
Defect item	Rank	Tests failing	Share	vs similar cars
Stop lamp: not working	#1	5,309	2.99%	1.46×
Coil spring: fractured or broken	#2	5,164	2.91%	1.30×
Wipers: does not clear the windscreen effectively	#3	4,975	2.81%	1.20×
Tread depth: tread depth below requirements of 1.6mm	#4	4,159	2.35%	1.26×
Position lamp: not working	#5	3,826	2.16%	1.00×
Washers: provides insufficient washer liquid	#6	3,792	2.14%	1.52×
Headlamp: not working on dipped beam	#7	3,213	1.81%	1.48×
Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits	#8	3,077	1.74%	2.22×
Headlamp aim: projected beam image is obviously incorrect	#9	3,061	1.73%	1.36×
Malfunction indicator lamp: inoperative or indicates a malfunction	#10	2,866	1.62%	1.42×
Ball joint: ball joint excessively worn	#11	2,653	1.50%	1.32×
Brake pads: less than 1.5 mm thick	#12	2,406	1.36%	0.94×
Service brake performance: excessively binding	#13	2,342	1.32%	1.71×
Headlamp aim: too low	#14	2,146	1.21%	1.11×
Condition: has a cut in excess of the requirements deep enough to reach the ply or cords	#15	1,991	1.12%	0.97×

Only the 150 most common national MOT failure items are compared; a rank counts every failure item recorded on the make.

How to use this

The list shows what a Smart is more likely than other cars to fail on, which is where to look on a pre-MOT check or a used-car inspection. The model pages break the same data down further — see Smart MOT pass rates by model.

Limitations

Official data: DVSA anonymised MOT results (2023–2024). 73 Auto analysis: expected failures apply the national rate of each item for the test's age, mileage band and fuel. MOT results reflect maintenance and use as well as design; they do not rank makes by reliability.

Check a Smart’s MOT history before you buy

Enter a registration to see which of these faults that particular car has failed or been advised on, and what it costs to run. Your first check is free and shows the vehicle summary and its headline ownership cost. The category-by-category breakdown is part of a paid check.

UK number plate or 17-character VIN

Where these figures come from

Anonymised MOT tests and results (2023 and 2024) — Driver and Vehicle Standards Agency (DVSA). Open Government Licence v3.0.

Figures labelled as 73 Auto estimates are our own analysis of these sources, set out in the methodology and data sources. To report a factual error, see corrections.