Smart (mcc)
39,688 MOT tests analysed. lands in the middle of the pack — here's where Forfours pass, fail, and end up on the retest sheet.
That's in line with the UK fleet average across our 1,984 tracked models.
Pass
78.0%
Pass-after-fix
4.7%
Fail
16.8%
Avg miles
45,542
Pass + Pass-after-fix + Fail = 100%
This model's production run straddles the January 2006 Euro 4 cutoff. Individual cars vary — check your registration plate on the government's ULEZ checker. Daily charges if driven in the zone: London £12.50 · Birmingham £8.00 .
Performance by cohort
2 year bands · 39,676 tests
Pass rate climbs 7.5 points across the cohorts — newer Forfour examples clear the test more reliably than the early cars.
Pass
76.6%
Fail
17.9%
PRS
4.9%
Avg mileage at test
49,157 mi
Pass
84.1%
Fail
11.8%
PRS
3.8%
Avg mileage at test
29,160 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
The Smart (mcc) Forfour is a petrol-powered car sold in the UK market across multiple generations, covering a broad date range in the test population.
MOT data from 27,191 tests puts this car on a 78.8% first-time pass rate, roughly in line with the UK fleet average. Average mileage at test is 41,564 miles. The most common fail item is tyre tread below the legal limit, followed by inoperative wiper blade.
Honest John owner records point to turbocharger reliability concerns as the recurring problems to check before buying used.
Buyers weighing up a used Forfour should treat the failure breakdown as a pre-purchase checklist. The pass rate is reasonable, but the gap between first attempt and a clean sheet narrows with age and mileage.
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Tyre tread depth not in accordance with the requirements
1,154 occurrences · 2.9% of tests
A suspension pin, bush or joint excessively worn
881 occurrences · 2.2% of tests
Lambda coefficient outside the default limits or the range specified by the manufacturer
673 occurrences · 1.7% of tests
Wiper blade missing or obviously not clearing the windscreen
666 occurrences · 1.7% of tests
A rear registration plate lamp or light source missing or inoperative in the case of multiple lamps or light sources
547 occurrences · 1.4% of tests
A tyre cords visible or damaged
512 occurrences · 1.3% of tests
a brake lining or pad worn below 1.5mm
481 occurrences · 1.2% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
459 occurrences · 1.2% of tests
Wiper blade defective
452 occurrences · 1.1% of tests
Stop lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning
436 occurrences · 1.1% of tests
Counts cover Major and Dangerous defects logged at test. Advisory items excluded so this shows why a car was rejected, not just what the tester flagged in passing.
Worst-case fix budget · top 4 failures
£168–£415
If every one of this Forfour's most-logged Major fails hit at the same MOT, that's the real-world UK garage range. Reality is usually one or two items, not all of them. Open the estimator →
Try the calculator
Build your own retest budget.
Year-band analysis
First-time MOT pass rate split by registration band. A 7.5-point gap between bands means the year you buy Smart (mcc) Forfour has a real effect on what turns up at the garage.
Best band to buy
84.1%
2018–2020 registration
the 2018–2020 band climbs to 84.1% — a 7.5-point improvement. Tests in this band average 29,160 miles — roughly 20K miles fewer on the clock than the older band. Failures here are mostly wear items: tread depth below requirements of 1.6mm, does not clear the windscreen effectively — the structural issues that drag down older examples don't appear in the top-10 for this band. The stricter post-2018 MOT test rules meant manufacturers had to tighten up emissions and electrical checks, but this band still shows far fewer major failures on suspension and bodywork than the older fleet.
Band to be cautious about
76.6%
Pre-2018 registration
On the older band (pre-2018), the data shows a 76.6% pass rate against a fleet average of 84.1% on the newer band. The main culprits logged at test: tread depth below requirements of 1.6mm, ball joint excessively worn, and lambda reading after 2nd fast idle outside…. Average mileage on test for this band is 49,157 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2018-2020 (84.1% first-time pass). Worst band to avoid: pre-2018 (76.6% pass). That's a 7.5-point spread across 32,530 older tests and 7,146 newer ones — year of build makes a material difference on this model.
Picked against this car's top failure patterns. Affiliate links to Amazon UK — we earn a small cut at no cost to you. Disclosed up-front, doesn't shape the data.
Item 01 · Amazon UK
Digital tyre-tread depth gauge
Five quid for a gauge beats £150 for a retest. UK MOT minimum is 1.6mm — most testers fail anything below 2mm to be safe.
Search Amazon UK
Item 02 · Amazon UK
Bosch Aerotwin wiper blades
Cheap wipers fail the test on smear streaks. Bosch Aerotwins last a winter and clear a screen properly.
Search Amazon UK
Item 03 · Amazon UK
H7 / W21W bulb pack
A spare-bulb kit lives in the boot. Test morning is not the time to find your stop-lamp's gone.
Search Amazon UK
My Motor World · affiliate
Affiliate links — small commission, no extra cost to you.
Click Mechanic · affiliate
Affiliate links — small commission, no extra cost to you.
Mobile mechanic · UK-wide
Book a mechanic at your door.
Fixed-price quotes upfront. No garage needed. Click Mechanic sends a vetted local mechanic to you — home, work, or roadside.
Owner reports · Honest John
Verbatim faults logged by owners on honestjohn.co.uk over recent years. We didn't summarise — these are the words people typed in.
What's good
Excellent turning circle. Easy to park thanks to compact si
Report of 2016 Smart Forfour 0.9 Turbo Proxy Premium Plus, bought used in March 2017, suffering a strange breakdown on the M1 northbound. "Deafening crack from the car simultaneous with the computer/satnav shutting down and a deafening clattering noise from the engine. Driver put ha
Source: honestjohn.co.uk · 1 reports indexed
Use the failure ranking as a pre-test checklist or a haggling lever. Treat the headline pass rate as a fleet-wide trend, not a guarantee on any individual car.
If you own a Forfour and your last MOT looked nothing like the ranked failures above, that's normal — individual cars vary widely. The ranking shows the patterns testers flag most often across the country.
