Used Mercedes-Benz A-Class W176 (2012–18) vs SEAT Leon Mk3 (2012–20)
Figures updated
Shopping for a used family hatchback? We compare the Mercedes-Benz A-Class W176 (2012–2018) and SEAT Leon Mk3 (2012–2020), which were on sale at the same time, on size, boot space, performance, safety and running costs, plus how cars of their age do in real MOT tests.
The short answer
The SEAT Leon Mk3 comes out ahead, with the better MOT record; the Mercedes-Benz A-Class W176 is close on everything else.
- The SEAT Leon Mk3 has the better MOT record for its age: the SEAT Leon Mk3 fails its MOT 10% less often than average for its age (21% of SEAT Leons built 2012–2020 failed first time in 2024, against 24% of all cars that age), while the Mercedes-Benz A-Class W176 fails its MOT 5% less often than average for its age (24% of Mercedes-Benz A-Classes built 2012–2018 failed first time in 2024, against 25% of all cars that age).
- Watch the seat belts and airbags on a Mercedes-Benz A-Class W176: it fails on them 2.7 times as often as the average car.
| Figure | Mercedes-Benz A-Class W176W176 (2012–2018), 5-door hatchback | SEAT Leon Mk3Mk3 (2012–2020), 5-door hatchback |
|---|---|---|
| Price and practicality | ||
| Body | 5-door hatchback | 5-door hatchback |
| Seats | – | 5 |
| BootSeats up / folded | – | 380 litres |
| Length | 4,292mm | 4,263mm |
| WidthWithout mirrors | 1,780mm | 1,810mm |
| Height | – | 1,446mm |
| Performance | ||
| Power | – | 86–184 PS |
| Safety | ||
| Euro NCAP ratingTests get tougher each year | ★★★★★ (2012) | ★★★★★ (2012) |
| Economy and emissions | ||
| Fuel types | – | – |
| Official economyVersions of this generation | – | – |
| CO2 | – | – |
| Running costs at 7,500 miles a year | ||
| Cheapest version to fuelWhichever fuel costs least | – | – |
| Car tax, registered 2001 to 2017Taxed on CO2; newer cars pay a flat £200 | – | – |
| Reliability from real MOT tests | ||
| Reliability score | 108Above average | 116Well above average (best) |
| Failed first time, cars of this generation's ageUK rate for cars the same age in brackets | 23.5% (24.8%)built 2012–2018 | 21.1% (23.6%)built 2012–2020 (best) |
| Failed MOT first time (ages 3–20) | 21.4% (best) | 23.6% |
| Failed at 3 years old | 10.2% (best) | 12.3% |
| Failed at 5 years old | 15.0% (best) | 18.3% |
| Failed at 10 years old | 29.7% | 24.3% (best) |
| Most common MOT fault | Tread depth (2.4% of tests) | Coil spring (2.8% of tests) |
| Fails more than average on | Seat belts and airbags (2.7×) | Nothing stands out |
| MOT tests analysed | 341,498 | 181,734 |
| About the cars | ||
| Type | Family hatchback | Family hatchback |
| Owners' average miles a year | 8,500 | 9,400 |
| On sale | 2012–2018 | 2012–2020 |
Green marks the better figure where the difference is more than 3%. Reliability figures cover every version of each model tested in the year. Running costs use the typical official economy of recent versions (WLTP where available); real-world economy is usually a little worse for every car.
More comparisons
- Ford Focus Mk3 vs Mercedes-Benz A-Class W176
- Volkswagen Golf Mk7 vs Mercedes-Benz A-Class W176
- Vauxhall Astra K vs Mercedes-Benz A-Class W176
- Audi A3 8V Sportback vs Mercedes-Benz A-Class W176
- Ford Focus Mk3 vs SEAT Leon Mk3
- Volkswagen Golf Mk7 vs SEAT Leon Mk3
- Vauxhall Astra K vs SEAT Leon Mk3
- Audi A3 8V Sportback vs SEAT Leon Mk3
Frequently asked questions
›Is a used Mercedes-Benz A-Class W176 or SEAT Leon Mk3 more reliable?
The SEAT Leon Mk3. Compared with all cars the same age, the SEAT Leon Mk3 fails its MOT 10% less often than average and the Mercedes-Benz A-Class W176 5% less often than average (DVSA MOT tests, 2024). Because they're different ages, their raw rates differ: 21.1% of SEAT Leons built 2012–2020 failed first time, and 23.5% of Mercedes-Benz A-Classes built 2012–2018. Whatever you buy, check the MOT history of the exact car.
›Which is bigger, the Mercedes-Benz A-Class W176 or the SEAT Leon Mk3?
The Mercedes-Benz A-Class W176 is 29mm longer (4,292mm against 4,263mm).
›Which is safer, the Mercedes-Benz A-Class W176 or the SEAT Leon Mk3?
Euro NCAP gave the Mercedes-Benz A-Class W176 5 stars (2012) and the SEAT Leon Mk3 5 stars (2012). Euro NCAP makes its tests tougher every few years, so ratings from different years aren't directly comparable.
›Should I buy the Mercedes-Benz A-Class W176 or the SEAT Leon Mk3?
The SEAT Leon Mk3 comes out ahead, with the better MOT record; the Mercedes-Benz A-Class W176 is close on everything else. The comparison above sets out price, space, performance, safety, running costs and reliability side by side.
Sources: manufacturers' UK specifications and price lists and Euro NCAP (listed on each model's page); DVSA anonymised MOT tests 2024 (Open Government Licence v3.0); Vehicle Certification Agency car fuel data, © Crown copyright, VCA cannot accept liability for its accuracy; fuel prices from the GOV.UK Fuel Finder scheme. Photos from Wikimedia Commons, credited under each picture.