Mercedes 420
Reliability, estimated running costs, and MOT data across 2 model years from 169 MOT tests in 2024.
Avg Pass Rate
76%
Total Tests
169
Model Years
1990 to 1991
Years Covered
2
About the Mercedes 420
The Mercedes 420 was MOT tested 169 times in 2024 (DVSA data, retests included) across 2 model years (1990 to 1991), with an average pass rate of 76%. That's 6 points below the average of 82% across all models in our data, so check the year-by-year data carefully before buying. Our records list petrol versions.
Mileage Across Years
The oldest model in our data (1990) averages 131,208 miles, while the newest (1991) averages 131,577 miles. Older models have covered serious mileage, so suspension and drivetrain wear are worth checking.
Compared to the Mercedes brand average of 87%, the 420 is 11 points lower, placing it among the less reliable Mercedes models.
Estimated Running Costs
Based on 7,400 miles/year, average pump prices of 174.57p petrol and 199.33p diesel (GOV.UK weekly road fuel prices, week of 19 October 2026), and MOT pass rate data. Insurance not included.
Full 1991 detailsHow reliable is the Mercedes 420?
Mercedes 420 by Year
Click any year to see detailed running costs, reliability data, and comparisons with similar cars.
Questions about the Mercedes 420
Is the Mercedes 420 reliable?
Across its 2 model years in our data (1990 to 1991), the Mercedes 420 averages a 76% MOT pass rate, from 169 tests (DVSA MOT data for tests in 2024, retests included). That's 6 points below the average of 82% across all models in the same data.
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