Mercedes-Benz 300: MOT pass rate and reliability data

The Mercedes-Benz 300 passes its MOT first time more often than the average UK car, by 3 percentage points. These figures come from the DVSA's full year of anonymised MOT results, covering 2,828 individual Mercedes-Benz 300 tests. Nothing here is an estimate or a survey.

The numbers

What this means if you are buying one

A 79.7% first-time pass rate means roughly 20 in every 100 Mercedes-Benz 300s presented for MOT fail on the first attempt. That is better than average, so a well-kept example is a reasonably safe used buy. The average Mercedes-Benz 300 tested had covered 113,799 miles and was built around 1990.

What this means at salvage auction

Pass rate is a proxy for what a car costs to keep on the road. The Mercedes-Benz 300 sits 3 points above the national average, ranked 1,450 of 2,005 models. On one bought as repairable salvage, the mechanical side is less likely to spring surprises, so your repair estimate should hold up reasonably well.

Before you bid: run the lot through the analyzer, check the car's own record, check the mileage, decode the VIN, and if it carries a marker use the write-off value calculator. Or compare it against another model.

Looking at a specific Mercedes-Benz 300 rather than the model in general? The free check covers its MOT and mileage history, and the full HPI report confirms the insurance write-off category, outstanding finance and whether it is recorded stolen, from licensed data for 5 credits. Already own one that has been damaged? Work out whether fixing it beats selling it with the repair or scrap calculator, and see recorded closing bids for damaged Mercedes-Benz 300s at UK salvage auction.

Most common MOT failures on a Mercedes-Benz 300

1. Emissions levels exceed default limits, 2.1% of tests (5.99x the national rate for this defect)
2. An obligatory rear fog lamp missing, or a front or rear fog lamp inoperative or in the case of a multiple light source more than 1/2 not functioning, 1.3% of tests (3.05x the national rate for this defect)
3. The strength or continuity of the load bearing structure within 30cm of any sub-frame, spring or suspension component mounting (a 'prescribed area') is significantly reduced or inadequately repaired, 2.8% of tests (2.99x the national rate for this defect)
4. Steering rack gaiter or ball joint dust cover missing or no longer prevents the ingress of dirt etc, 1.7% of tests (2.28x the national rate for this defect)
5. A direction indicator lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning, 1.5% of tests (2.27x the national rate for this defect)
6. Significant brake effort recorded with no brake applied indicating a binding brake, 1.9% of tests (1.84x the national rate for this defect)
7. The aim of a headlamp is not within limits laid down in the requirements, 3.8% of tests (1.62x the national rate for this defect)
8. Windscreen washers not working or not providing sufficient fluid to clear the windscreen, 2.4% of tests (1.4x the national rate for this defect)
9. Exhaust system leaking or insecure, 1.4% of tests (1.36x the national rate for this defect)
10. Brake pipe damaged or excessively corroded, 1.3% of tests (1.26x the national rate for this defect)

From 2,830 DVSA-tracked Mercedes-Benz 300 tests, 2024. DVSA testers marked 2.94% of these flagged Mercedes-Benz 300 defects as "dangerous", meaning the tester judged the car unsafe to drive away, against 5.11% nationally.

Most common MOT advisories on a Mercedes-Benz 300

An advisory doesn't fail the car - the tester flags it as worth watching, but it still passes. A different list from the failures above: what testers are noting on a Mercedes-Benz 300 before it actually fails on it.

1. A wheel bearing with excessive play, 5.7% of tests (8.77x the national rate for this advisory)
2. A flexible brake hose excessively damaged, deteriorated, chafed, twisted or stretched, 3.3% of tests (5.86x the national rate for this advisory)
3. Vehicle structure corroded to the extent that the rigidity of the assembly is seriously reduced, 4.1% of tests (3.27x the national rate for this advisory)
4. Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users, 18% of tests (3.23x the national rate for this advisory)
5. A brake hose ferrule excessively corroded, 4.1% of tests (3.22x the national rate for this advisory)
6. The strength or continuity of the load bearing structure within 30cm of any sub-frame, spring or suspension component mounting (a 'prescribed area') is significantly reduced or inadequately repaired, 4.6% of tests (3.05x the national rate for this advisory), also fails
7. Brake pipe damaged or excessively corroded, 18.6% of tests (3x the national rate for this advisory), also fails
8. Exhaust system leaking or insecure, 6.3% of tests (2.2x the national rate for this advisory), also fails
9. A spring or spring component fractured or seriously weakened, 9.9% of tests (2.09x the national rate for this advisory)
10. Significant brake effort recorded with no brake applied indicating a binding brake, 3.4% of tests (1.7x the national rate for this advisory), also fails

From 2,830 DVSA-tracked Mercedes-Benz 300 tests, 2024.

Mercedes-Benz 300 pass rate by model year

From its 1990 to its 1992 model year, the Mercedes-Benz 300's first-time pass rate has fallen 0.1 points, from 80.4% to 80.3%, an unusual pattern where even its newest years fail more than its oldest. First-time pass rate for each Mercedes-Benz 300 year:

• 1990 Mercedes-Benz 300 - 80.4% first-time pass, 301 tests
• 1991 Mercedes-Benz 300 - 77.6% first-time pass, 361 tests
• 1992 Mercedes-Benz 300 - 80.3% first-time pass, 376 tests
• 1993 Mercedes-Benz 300 - 81.2% first-time pass, 202 tests

Mercedes-Benz 300 by fuel type

The Mercedes-Benz 300's two most-tested fuel types split by 5.8 points: petrol passes first time 81.9% of the time (2,254 tests) against 76.1% for diesel (522 tests).

• Petrol Mercedes-Benz 300 - 81.9% first-time pass, 2,254 tests
• Diesel Mercedes-Benz 300 - 76.1% first-time pass, 522 tests

Other Mercedes-Benz models

• Mercedes-Benz C - 77.4%
• Mercedes-Benz A-Class - 78.7%
• Mercedes-Benz E - 79.2%
• Mercedes-Benz A - 89.5%
• Mercedes-Benz Vito - 72.7%
• Mercedes-Benz Gla - 85.2%
• Mercedes-Benz Glc - 87.8%
• Mercedes-Benz B-Class - 74.7%

Models with a similar pass rate

• Renault Captur - 79.7%
• Toyota Verso - 79.7%
• Volkswagen Amarok - 79.7%
• Renault Trafic Sl28 B-Ness Energy Dci - 79.7%
• BMW 130 - 79.7%
• Dacia Duster - 79.6%

If this car is a salvage or write-off

• What does Cat N mean? Category N explained
• What does Cat S mean? Category S explained
• Cat S vs Cat N: the real differences
• Do you need an HPI check on a car you know is a write-off?

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All 2,005 models ranked by MOT pass rate