Mercedes Benz
C 320
2,602 MOT tests analysed. lands in the middle of the pack — here's where C 320s pass, fail, and end up on the retest sheet.
That's 4.4 points below the UK fleet average across our 1,984 tracked models — buyers should expect more first-time fails than the typical UK car.
Pass
73.1%
Pass-after-fix
4.3%
Fail
21.6%
Avg miles
118,002
Pass + Pass-after-fix + Fail = 100%
Diesel cars registered before September 2015 are typically pre-Euro 6 — subject to daily charges in London ULEZ (£12.50), Birmingham CAZ (£8), Bristol CAZ (£9), and Glasgow LEZ. Daily charges if driven in the zone: London £12.50 · Birmingham £8.00 · Bristol £9.00 .
The picture
C 320: a below-average pass rate worth digging into
Across 1,867 MOT tests, the C 320 returns 69.5% first-time pass — well below the UK fleet average. The single most-logged Major fail is a broken or weak spring. Worn suspension bushes and windscreen damage round out the top three. Average tested mileage sits at 114,171, which is the lens to read those failure rankings through. If you own one and the next test is close, the ranked list below is a sensible pre-test checklist.
ABI Insurance Group
Group 28–44
A high-group car — insurance costs will be significantly above average. Lower groups cost less to insure; UK fleet average is around Group 22.
Source: ABI Group Rating Panel · administered by Thatcham Research · groups cover standard variants; performance trims may sit higher. Browse all insurance groups →
28–44
out of 50
Top ten reasons for rejection.
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- 01
A suspension pin, bush or joint excessively worn
159 occurrences · 6.1% of tests
- 02
A spring or spring component fractured or seriously weakened
90 occurrences · 3.5% of tests
- 03
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
89 occurrences · 3.4% of tests
- 04
Brake pipe damaged or excessively corroded
87 occurrences · 3.3% of tests
- 05
A suspension joint dust cover severely deteriorated
64 occurrences · 2.5% of tests
- 06
Tyre tread depth not in accordance with the requirements
62 occurrences · 2.4% of tests
- 07
A rear registration plate lamp or light source missing or inoperative in the case of multiple lamps or light sources
54 occurrences · 2.1% of tests
- 08
A suspension joint dust cover missing or no longer prevents the ingress of dirt etc
54 occurrences · 2.1% of tests
- 09
A suspension joint dust cover severely deteriorated
49 occurrences · 1.9% of tests
- 10
Headlamp reflector or lens slightly defective
48 occurrences · 1.8% 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
£280–£810
If every one of this C 320'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 →
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Build your own retest budget.
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Owner reports · Honest John
What owners actually report.
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
Much improved interior quality. More refined and better to drive than predecessor. Strong 2.0-litre four-cylinder diesel engines on facelifted cars.
Where it falls short
C220 CDI with automatic gearbox is disappointing. Surprising quality issues with pre-facelift models.
Recent owner-reported faults
- 19 Oct 2020
Report of electric steering motor failure on 2016 C-Class. Dealer recommends replacing the full steering rack as the motor is part of the component. £2200 for reconditioned unit fitted. Mercedes-Benz UK has offered to cover 50 per cent of the repair cost.
- 23 Feb 2020
Owner of 220 diesel reports a 9mpg drop in fuel economy after voluntary dealer emissions update.
- 20 Jan 2020
Further report of front wheels of April 2019 Mercedes Benz C43 AMG "skipping badly when manoeuvring at very low speed resulting in a disconcertingly loud noise akin to having collided with a kerb."
- 3 Jan 2020
Report of failure of the brakes of 2105 Mercedes Benz C300 D BlueTec hybrid at 88,000 miles. The servo assistance vacuum pump had failed. Needed attention by MB dealer because MB independent not qualified to work on a hybrid. Marshall Care Plan B warranty taken out when car was bought not pay out as it's not a listed part.
- 17 Dec 2019
Report of rattle from engine of Mercedes-Benz C200 EQ Boost (48v mild hybrid) purchased in May 2019. Within a couple of weeks owner reported a "serious engine rattle" to the supplying Mercedes dealer who said there was nothing wrong with. He then got management involved and they changed a pulley, belt and tensioner, but it made no difference. They then got their group technician involved. He submitted his findings to Mercedes-Benz and they fitted a redesigned crank pulley, but again the noise did not improve so owner served a rejection letter on the dealership and they submitted an exchange vehicle application, but Mercedes said there’s nothing wrong with the car as they have been able to reproduce the noise in some of the other C200 EQ Boosts and they can do some things to reduce the noise.
- 24 Nov 2019
Report of transmission failure of 2005/65 Mercedes Benz W205 C220 automatic at 35,000 miles; car correctly serviced on time by the MB dealer. Part to repair quoted at £1200 + labour (total of £1,644). MB is not initially offering any help towards cost from a goodwill view point. Car is 8 months out of manufacturer warranty, but owner may have Sale of Goods case law rights.
- 15 Nov 2019
Report that after the NOx emissions software update a Mercedes-Benz C250d 4matic will not shift up from 8th to 9th gear until 75mph (previously 68mph). 9th can be selected on the paddles, but box shifts back down to 8th at about 65mph.
- 25 Oct 2019
Report of front wheels of Mercedes-Benz C43 4-Matic 'skipping'.
- 9 Sep 2019
Report of smell of petrol outside February 2015 Mercedes Benz C200 Sport auto. Will be a blocked charcoal filter in the fuel tank breather system.
- 4 May 2019
Petrol smell reported from March 2016 Mercedes Benz W205 C200 only just out of warranty. Car had its last service with Mercedes in the middle of March. Owner reported to dealer in April 2019 and dealer had the cheek to inform him there would be a £165 'diagnosis fee' to establish the cause of what is actually a very well known problem of the carbon filter in the fuel tank breathing system becoming blocked. Shoud be fixed FoC. Same thing happens on A-Class.
- 22 Apr 2019
Complaint of 2017 Mercedes-Benz C43 AMG 4-Matic clunking its front tyres on full lock. 4,000 miles from new. Been back to the local Mercedes dealer for investigation under warranty but returned in same the same condition. There are two cures. One is different tyres. But the correct cure is a replacement steering knuckle joint that is correctly engineered for RHD cars.
- 21 Oct 2018
High speed vibration reported from C350e, particularly noticeable on smooth motorways. Owner has chenged tyres and has a 4-way laser alignment to no avail. MB dealer puzzled. No problem with Airmatic suspension. Seems to be driveline.
Source: honestjohn.co.uk · 30 reports indexed, top 12 shown
Buying or keeping a C 320?
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 C 320 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.