BMW 3 Series vs Mercedes-Benz C-Class: which is the better used buy?

On DVSA MOT records the BMW 3 Series is the more reliable used buy: it passes its first MOT 3.0 percentage points more often than the Mercedes-Benz C-Class once both are compared against what the national fleet scores at the same age. That comparison covers 80,075 real tests, not a survey.

MOT first-time pass rate

Counted from DVSA’s anonymised MOT test records. “vs age-matched” compares each model against what the national fleet scores at the same age — the only fair better-or-worse number, because an older fleet fails more whatever its build quality.

Model	Pass rate	Age-matched national	Difference	Tests
BMW 3 Series	79.1%	73.5%	+5.6	42,657
Mercedes-Benz C-Class	78.6%	76%	+2.6	37,418

Source: DVSA MOT Anonymised Data 2025 (Open Government Licence v3.0). National first-time pass rate 77.3%. Applies to Great Britain — Northern Ireland is tested by the DVA under a separate manual.

BMW 3 Series

F30 (2012–2019) / G20 (2019–present) · D-segment executive saloon and touring estate. The most popular used premium car in the UK by volume. Available in a wide range of engines: 316i, 318i, 320i, 330i petrols; 316d, 318d, 320d, 330d diesels; 330e plug-in hybrid. Saloon, Touring (estate), and Gran Turismo body styles.

The BMW 3 Series is one of the best driver's cars in its segment but requires disciplined maintenance to avoid expensive repairs. The 320d diesel is by far the most popular UK-market variant — reliable at motorway mileage but requires a full service and timing chain history. The N47 diesel engine (pre-2015) had a timing chain tensioner failure issue at the rear of the engine — an expensive repair. The B47 diesel (post-2015) is significantly more reliable. On petrols, the B48 (post-2015 G20) is excellent. The key rule: full BMW dealer or BMW-specialist service history is essential. An unmaintained 3 Series is an expensive liability.

What goes wrong

N47 diesel timing chain failure (F30 2012–2015)critical
Chain rattle on cold start; rattling from rear of engine; engine management light; in severe cases, sudden engine failure
F30 2012–2015 with N47 diesel (316d, 318d, 320d) · From 60,000 miles; can occur earlier if oil changes were delayed · £3,000–£6,000 timing chain replacement (rear-mounted chain requires engine removal); up to £10,000+ if the chain has jumped and damaged the engine
Check: This is the single most critical check on any F30 N47 diesel. The N47 chain is rear-mounted — listen for chain rattle at idle with the bonnet up. Ask for proof of timing chain replacement in the service history. If the chain has not been replaced and the car has over 75,000 miles, budget for the repair or walk away. The B47 diesel (post-2015 on the F30 facelift and all G20) is unaffected.
Electric water pump failure (N20/B46/B48 petrols)major
Coolant warning light; engine overheating; steam from engine bay; loss of heat from heater
F30 2012–2019 petrol models (N20 engine) · From 50,000 miles; often fails between 60,000–95,000 miles · £600–£1,200 water pump replacement
Check: Check coolant level and condition. Ask about any history of overheating or coolant warning lights. The electric water pump on N20 engines is a known maintenance item — not catastrophic if caught early, but a failed pump can cause overheating if ignored. Budget for proactive replacement on high-mileage N20 cars.
320d/318d high-pressure fuel pump failure (N47)major
Hard starting; rough idle; engine cutting out; fuel pressure fault codes
F30 N47 diesel 2012–2015 · Above 75,000 miles · £800–£1,500 high-pressure fuel pump replacement
Check: Check for any hesitation or hard-starting behaviour on the test drive. N47 high-pressure fuel pump failures are common above 75,000 miles. If this is a known issue on the specific car, negotiate accordingly.
EGS automatic gearbox selector module failure (ZF 8HP)moderate
Gearbox warning light; "Transmission malfunction" message; car stuck in one gear; intermittent gear selection issues
F30 2012–2019 (ZF 8-speed automatic) · Above 60,000 miles · £400–£1,200 EGS module replacement; ZF gearbox service (fluid + filter) £300–£500
Check: Test the automatic gearbox through its full range — all gears, Sport mode, manual paddle shifts. Any hesitation, warning lights, or erratic behaviour requires investigation. Ask for ZF gearbox service history (fluid change every 35,000 miles prolongs life significantly).

Typical asking price:: F30 2015–2018 320d: £8,000–£15,000 | F30 2018–2019 facelift: £12,000–£18,000 | G20 2019–2022: £15,000–£28,000
Real-world economy:: 47–57 mpg (320d real-world UK mixed motorway); 35–44 mpg (320i petrol real-world)
Vehicle tax:: £200/year standard rate from the second year, hybrids included — the alternative-fuel discount ended on 1 April 2025. Cars registered 2001–2017 pay a CO2 band, roughly £20–£790/year (2026/27 rates).
Best years:: 2019, 2020, 2021, 2022
Years to avoid:: 2012, 2013, 2014

Full 3 Series fault guide Used BMWs

Mercedes-Benz C-Class

W205 (2014–2021) / W206 (2021–present) · D-segment executive saloon, estate (T-Model), and coupe (C205). Direct competitor to BMW 3 Series and Audi A4. Available with petrol (C180, C200, C300), diesel (C200d, C220d, C300d), and PHEV (C300e/de) engines. One of the most popular used premium cars in the UK.

The Mercedes C-Class W205 is a beautifully built executive car but has a significantly higher incidence of electrical faults, AIRMATIC suspension issues, and engine oil leak problems than the BMW 3 Series or Audi A4 at comparable mileage. The M274 engine (C200, C250) had documented timing chain issues pre-2016. The OM651 diesel (C220 CDI pre-2016) had oil leaks and high-pressure pump failures. The W205 C-Class requires a good independent Mercedes specialist to keep running costs manageable — main dealer servicing is expensive. The post-2019 facelift is significantly more reliable than launch cars.

What goes wrong

M274 engine timing chain (C200/C250 petrol, pre-2016)critical
Rattling on cold start from the rear of the engine; timing-related engine management codes; rough running
W205 2014–2016 with M274 engine (C180, C200, C250) · From 50,000 miles; higher risk above 60,000 miles · £1,500–£3,500 timing chain replacement; more if engine damage has occurred
Check: Listen for chain rattle on cold start. Check the service history for evidence of the M274 updated timing chain tensioner being applied. Post-2016 W205 models use the updated M274 specification — significantly lower risk.
AIRMATIC suspension failure (C-Class with AIRMATIC option)major
"Car too low" warning; suspension compressor noise; car sits unevenly; ride height varies after standing overnight
2014–2021 (W205 with AIRMATIC air suspension option) · From 50,000 miles; risk increases with age (rubber bladders degrade) · £600–£1,200 per air strut; £400–£800 compressor; £200–£400 ride height sensors
Check: Check whether the car has AIRMATIC air suspension or conventional coil springs (AMG Line and higher trims are more commonly AIRMATIC). If AIRMATIC: walk around the car on level ground and check it sits evenly. Listen for compressor noise on startup. AIRMATIC repairs are one of the highest-cost common fault areas on used W205s. Cars with conventional springs avoid this entirely.
7G-Tronic Plus automatic gearbox valve body faultsmajor
Jerky or hesitant gear changes; gearbox warning light; car stuck in one gear; delayed response from standstill
2014–2018 (7G-Tronic Plus) · Above 50,000 miles; can appear earlier without service · £600–£1,200 valve body replacement; £300–£500 gearbox fluid and filter service
Check: Test all gear ranges on the test drive, including manual mode paddle-shift. Any hesitation or warning lights require investigation. The 7G-Tronic Plus valve body is a known wear item on high-mileage W205s without regular gearbox servicing.
Oil leaks (OM651 diesel, C220 CDI pre-2016)moderate
Oil visible on engine underside; oil smell when stationary; oil level dropping between services
2014–2016 (C220 CDI with OM651 diesel) · Above 60,000 miles · £300–£800 turbo oil feed pipe seal; rocker cover gasket £200–£400
Check: Check the underside of the engine during a pre-purchase inspection for oil residue — especially around the turbocharger oil feed pipe and rocker cover. OM651 oil leaks are a documented weakness on high-mileage cars.

Typical asking price:: W205 2015–2018 C220d: £9,000–£16,000 | W205 2019–2021 facelift: £15,000–£24,000 | C300e PHEV: £18,000–£27,000
Real-world economy:: 49–57 mpg (C220d real-world UK motorway); 38–44 mpg (C200 petrol real-world)
Vehicle tax:: £200/year standard rate from the second year, hybrids included — the alternative-fuel discount ended on 1 April 2025. Cars registered 2001–2017 pay a CO2 band, roughly £20–£790/year (2026/27 rates).
Best years:: 2019, 2020, 2021
Years to avoid:: 2014, 2015, 2016

Full C-Class fault guide Used Mercedes-Benzs

Which one suits you

BMW 3 Series

Good for: Buyers who want a genuine driver's car and are prepared to maintain it properly. Motorway-mile buyers who will use the 320d's diesel efficiency on long UK commutes. Buyers with a BMW specialist garage lined up for servicing.

Less good for: Buyers who want the lowest total cost of ownership — a Toyota Corolla or Skoda Octavia will cost meaningfully less to run. F30 N47 diesel buyers without verified timing chain history — this is a potentially catastrophic repair. First-time BMW buyers who plan to service it at the cheapest possible garage — BMW models require BMW-specific knowledge and fluids.

Mercedes-Benz C-Class

Good for: Buyers who want Mercedes-Benz prestige and build quality and will use a specialist for servicing. Post-2019 W205 facelift buyers with documented service history. C300e PHEV buyers with home charging who want a premium PHEV at this price point.

Less good for: Buyers looking for the lowest total cost of ownership in the executive segment — the BMW 3 Series and Audi A4 are less expensive to maintain. W205 2014–2016 buyers without verified timing chain history on M274 engines. Cars with AIRMATIC suspension without recent AIRMATIC service history.

Frequently Asked Questions

Which is more reliable, the BMW 3 Series or the Mercedes-Benz C-Class?

The BMW 3 Series. It passes its first MOT 3.0 percentage points more often than the Mercedes-Benz C-Class once both are age-adjusted, across 80,075 DVSA-recorded tests.

What is the MOT pass rate for the BMW 3 Series?

79.1% of BMW 3 Seriess pass their MOT first time, from 42,657 tests in DVSA's records. The national first-time rate is 77.3%, but cars of this model's age average 73.5% — so it runs 5.6 points better than its age group.

What is the MOT pass rate for the Mercedes-Benz C-Class?

78.6% of Mercedes-Benz C-Classs pass their MOT first time, from 37,418 tests. Against the 76% that cars of its age average, it runs 2.6 points better.

Which years should I avoid?

For the BMW 3 Series, 2012–2014 F30 with N47 diesel: the N47 2.0-litre diesel used in 316d, 318d, and 320d had a rear-mounted timing chain that stretched and failed prematurely, often at 60,000–95,000 miles. The repair requires removing the engine — costs of £3,000–£6,000 were common. Many N47 engines were replaced under extended warranty or goodwill; survivors without documented chain replacement are high-risk. For the Mercedes-Benz C-Class, 2014–2016 launch cars: highest incidence of M274 timing chain issues, gearbox 7G-Tronic valve body problems, panoramic roof seal leaks, and electrical fault reports. The OM651 diesel used in early C220 CDI also had documented oil leaks from the turbo feed pipe.

Which is cheaper to run?

The BMW 3 Series returns 47–57 mpg (320d real-world UK mixed motorway); 35–44 mpg (320i petrol real-world) in real UK driving; the Mercedes-Benz C-Class returns 49–57 mpg (C220d real-world UK motorway); 38–44 mpg (C200 petrol real-world). Vehicle tax: 3 Series — £200/year standard rate from the second year, hybrids included — the alternative-fuel discount ended on 1 April 2025. Cars registered 2001–2017 pay a CO2 band, roughly £20–£790/year (2026/27 rates).; C-Class — £200/year standard rate from the second year, hybrids included — the alternative-fuel discount ended on 1 April 2025. Cars registered 2001–2017 pay a CO2 band, roughly £20–£790/year (2026/27 rates).. Insurance differs mainly by driver and postcode rather than by model, so treat any model-level insurance figure with caution.

MOT figures are counted from DVSA records and are the only measured statistic here. Prices, economy and tax bands are indicative and vary by specification, condition and where the car has lived. Last reviewed: 2026-08-14 / 2026-08-14.