Mercedes-benz 420 Reliability, MOT Pass Rate & Common Faults
Free Mercedes-benz 420 car check
Is the Mercedes-benz 420 reliable? We analysed 24,311 real MOT tests across 2,343 vehicles to find out.
Got a specific Mercedes-benz 420? Enter the reg for a free check:
The Mercedes-benz 420 is above average for reliability based on real UK MOT data. Common problems include suspension component mounting prescribed area is excessively corroded, brake pipe excessively corroded and tyre tread depth below requirements of 1.6mm. Here's everything you need to know before buying a used Mercedes-benz 420.
Mercedes-benz 420 Number Plates
Number plates registered to a Mercedes-benz 420. Click on any registration for full vehicle details — including MOT history, mileage records, previous owners and damage history.
Mercedes-benz 420 MOT Pass Rate by Year
How likely is a Mercedes-benz 420 to pass its MOT? Here's the pass rate for each registration year, newest first.
Mercedes-benz 420 Problems — What Goes Wrong?
The most common reasons a Mercedes-benz 420 fails its MOT, ranked by how often they occur. Check for these problems before you buy.
Mercedes-benz 420 Mileage — What's Normal?
How many miles does a typical Mercedes-benz 420 owner drive per year? Use this to check if a car you're looking at has suspiciously low or high mileage.
Mercedes-benz 420 MOT Data by Registration Year
Full breakdown of pass rate and mileage for each year. Use this to compare the Mercedes-benz 420 year you're looking at.
| Year | Tests | Pass Rate | Low Mi. | Typical Mi. | High Mi. |
|---|---|---|---|---|---|
| 2007 | 72 | 81.9% | 59,599 | 85,066 | 106,560 |
| 1998 | 91 | 71.4% | 52,540 | 89,676 | 168,744 |
| 1997 | 53 | 66.0% | 84,866 | 148,404 | 169,238 |
| 1992 | 366 | 77.3% | 101,031 | 117,497 | 143,113 |
| 1991 | 1,167 | 74.2% | 93,701 | 125,557 | 153,881 |
| 1990 | 1,974 | 74.6% | 106,946 | 133,525 | 162,107 |
| 1989 | 4,360 | 78.1% | 72,662 | 104,245 | 134,682 |
| 1988 | 5,952 | 75.3% | 71,722 | 101,568 | 132,811 |
| 1987 | 5,734 | 75.9% | 73,621 | 100,068 | 131,118 |
| 1986 | 3,447 | 75.0% | 73,046 | 107,080 | 141,810 |
| 1980 | 227 | 69.2% | 78,932 | 104,450 | 134,609 |
| 1979 | 212 | 74.1% | 57,679 | 102,497 | 143,418 |
| 1978 | 65 | 64.6% | 101,195 | 135,125 | 146,371 |
How Long Does a Mercedes-benz 420 Last?
Based on 2,343 Mercedes-benz 420 vehicles on UK roads.
Mercedes-benz 420 Mileage Distribution
Total mileage recorded across all Mercedes-benz 420 MOT tests. If the car you're looking at is above the 75th percentile, it's done more miles than most.
Best Year to Buy a Used Mercedes-benz 420
Based on MOT pass rates across all registration years with sufficient test data.
81.9% MOT pass rate from 72 tests
64.6% MOT pass rate from 65 tests
The best year to buy a used Mercedes-benz 420 is 2007, which has the highest MOT pass rate at 81.9% across 72 tests. The 1978 model year has the lowest pass rate at 64.6% — if you're looking at one from that year, budget for potential repairs and get a thorough pre-purchase inspection.
How Does the Mercedes-benz 420 Compare?
MOT pass rates compared to similar models. Click any model for the full breakdown.
| Model | Pass Rate | Tests | Typical Mileage | Lifespan |
|---|---|---|---|---|
| Mercedes-benz 420 THIS CAR | 75.7% | 24,311 | 106,332 mi | 40 yrs |
| Mercedes-benz C | 77.6% | 8,031,355 | 77,082 mi | 32 yrs |
| Mercedes-benz E | 79.4% | 4,722,746 | 83,960 mi | 33 yrs |
| Mercedes-benz A-class | 77.6% | 4,204,702 | 57,023 mi | 28 yrs |
| Mini Mini Cooper | 72.2% | 12,546 | 83,718 mi | 25 yrs |
Compared to the Mercedes-benz C (77.6% pass rate) and the Mercedes-benz E (79.4% pass rate), the Mercedes-benz 420 trails behind on MOT reliability.
Found a Mercedes-benz 420 you like?
Run a full vehicle history check on the specific car. See finance, stolen, write-off, mileage and MOT data for that exact vehicle.
Check a specific Mercedes-benz 420Should you buy a used Mercedes-benz 420?
The Mercedes-benz 420 has an overall MOT pass rate of 75.7% across 24,311 real MOT tests — comfortably above the UK average, which puts it among the more reliable models on UK roads.
The most common problems on the Mercedes-benz 420 are suspension component mounting prescribed area is excessively corroded (647 recorded failures), brake pipe excessively corroded (577), and tyre tread depth below requirements of 1.6mm (565). These are the faults most likely to cause an MOT failure on this model, so check for them carefully on any test drive or pre-purchase inspection. Many are wear-and-tear items that can be budgeted for, but a car that's already failing on multiple fronts may signal neglected maintenance.
A typical Mercedes-benz 420 owner drives around 809 miles per year. If the car you're looking at is significantly above this, expect more wear on suspension, brakes and tyres. If it's well below, the vehicle may have been sitting unused — check for perished rubber, corroded discs and stale fluids.
In terms of longevity, most Mercedes-benz 420 models stay on UK roads for around 40 years — a strong showing that suggests solid build quality and readily available parts. If you're buying one that's already approaching that window, the data suggests it has plenty of life left provided it's been maintained.
Before committing to a purchase, we recommend running a full vehicle history check on the specific car. This will reveal any outstanding finance, stolen markers, write-off history and mileage discrepancies that the seller may not disclose — and that the MOT data alone can't tell you.