Mercedes-Benz 300
From 7,890 MOT tests. Above average for its class.
Common MOT failure categories
Pass rate by registration year
Older 300s fare better: 1993 models pass at 79% vs 84.1% for 1987.
Pass rate by fuel type
What goes wrong?
The most common MOT failure reasons are the aim of a headlamp is not within limits laid down in the requirements, 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 and windscreen washers not working or not providing sufficient fluid to clear the windscreen. The top issue, the aim of a headlamp is not within limits laid down in the requirements, caused 205 failures in 2024. If you need repairs before retesting, sites like BookMyGarage let you compare local prices.
| the aim of a headlamp is not within limits laid down in the requirements | 205 |
| 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 | 145 |
| windscreen washers not working or not providing sufficient fluid to clear the windscreen | 129 |
| a lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning | 117 |
| emissions levels exceed default limits | 115 |
| a suspension joint dust cover missing or no longer prevents the ingress of dirt etc | 111 |
| wiper blade missing or obviously not clearing the windscreen | 99 |
| significant brake effort recorded with no brake applied indicating a binding brake | 97 |
| a suspension joint dust cover severely deteriorated | 89 |
| steering rack gaiter or ball joint dust cover missing or no longer prevents the ingress of dirt etc | 87 |
How serious are these failures?
Not all MOT failures are equal. Only 20.3% of 300 failures are serious (safety or roadside), below the 44.4% average. When this car fails its MOT, it's more likely to be lights, wipers, or emissions than something dangerous. When it does fail, the average repair bill is around £81.
Fuel type matters
Petrol versions pass at 80.7% while Diesel versions pass at 74.1%, a 7 percentage point gap.
Mercedes-Benz 300 on UK roads
The fleet is shrinking: 403 scrapped or exported in the past year with only 14 newly registered, a net loss of 389. At this rate, roughly 36.8 years until none remain. Now at 20.2% of its peak (69,215 in 1999 Q4).
Quarterly breakdown
| Quarter | On road | SORN | New | Gone | Net |
|---|---|---|---|---|---|
| 2025 Q3 | 5,145 | 8,822 | +3 | -25 | -22 |
| 2025 Q2 | 5,171 | 8,818 | +4 | -0 | +14 |
| 2025 Q1 | 4,658 | 9,317 | +1 | -112 | -111 |
| 2024 Q4 | 4,741 | 9,345 | +6 | -266 | -260 |
| 2024 Q3 | 5,279 | 9,067 | +5 | -87 | -82 |
| 2024 Q2 | 5,367 | 9,061 | +4 | -0 | +144 |
| 2024 Q1 | 4,929 | 9,355 | +1 | -209 | -208 |
| 2023 Q4 | 4,950 | 9,542 | +6 | -130 | -124 |
20 variants on the road
| Variant | Fuel | Licensed | Share |
|---|---|---|---|
| 300 Sl Auto | Petrol | 1,095 | 26% |
| 380 Sl Auto | Petrol | 477 | 11% |
| 350 Sl Auto | Petrol | 443 | 11% |
| 350 Sl | Petrol | 314 | 7% |
| 312D Lwb | Diesel | 307 | 7% |
| 300 Se Auto | Petrol | 239 | 6% |
| 300Sl Auto | Petrol | 203 | 5% |
| 300Sl-24 Auto | Petrol | 197 | 5% |
| 308D Lwb | Petrol | 186 | 4% |
| 300Ce Auto | Petrol | 91 | 2% |
| 300D Diesel Auto | Petrol | 91 | 2% |
| 300 | Battery Electric | 84 | 2% |
| 380 Slc Auto | Petrol | 65 | 2% |
| 310 Van | Diesel | 64 | 2% |
| 300Te Auto | Petrol | 61 | 1% |
| 300 Gd M2 | Diesel | 58 | 1% |
| 300 Se | Diesel | 57 | 1% |
| 308D | Diesel | 53 | 1% |
| 300 Ce Auto | Petrol | 51 | 1% |
| 300 Td | Diesel | 51 | 1% |
Source: DfT vehicle licensing statistics, 2025 Q3. Crown copyright, OGL v3.0.
By registration year
| Year | Pass rate | Top failures |
|---|---|---|
| 1993 | 79% | a steering ball joint with excessive wear or free play, emissions levels exceed default limits |
| 1992 | 79.7% | the aim of a headlamp is not within limits laid down in the requirements, a lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning |
| 1991 | 75.4% | a lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning, the aim of a headlamp is not within limits laid down in the requirements |
| 1990 | 78.4% | a lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning, steering rack gaiter or ball joint dust cover missing or no longer prevents the ingress of dirt etc |
4 earlier years
| 1989 | 81.3% | windscreen washers not working or not providing sufficient fluid to clear the windscreen, the aim of a headlamp is not within limits laid down in the requirements |
| 1988 | 80.9% | the aim of a headlamp is not within limits laid down in the requirements, a suspension joint dust cover missing or no longer prevents the ingress of dirt etc |
| 1987 | 84.1% | the aim of a headlamp is not within limits laid down in the requirements, 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 |
| 1986 | 76.3% | 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, a suspension joint dust cover severely deteriorated |
Typical mileage
Half of all 300s tested had between 78,404 and 157,480 miles on the clock. A significant number are high-mileage vehicles.
At 104,749 median miles, the 300 has 0.02 failures per 10,000 miles driven.
Other Mercedes-Benz models
Common questions
What is the Mercedes-Benz 300 MOT pass rate?
The Mercedes-Benz 300 has a 79.5% MOT pass rate based on 7,890 real MOT tests. This is above the national average.
What are common MOT failures on a Mercedes-Benz 300?
The most common MOT failure on the Mercedes-Benz 300 is the aim of a headlamp is not within limits laid down in the requirements, which caused 205 failures. Other common issues include 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.
How many Mercedes-Benz 300s are on UK roads?
There are 5,145 Mercedes-Benz 300s currently licensed on UK roads, with 8,822 on SORN.
What is the typical mileage of a Mercedes-Benz 300 at MOT?
The median mileage at MOT for a Mercedes-Benz 300 is 104,749 miles. The middle 50% of vehicles tested have between 78,404 and 157,480 miles.
Buying a used 300?
Start with the free tools. Look up the specific vehicle's MOT history on GOV.UK The mileage at each test will show if it's been wound back, and the advisory history tells you what's wearing. Cross-reference that against the typical failures above to see if anything looks unusual for this model.
The free data won't tell you about outstanding finance, theft markers, or write-off history. For that, you need a vehicle history check This is especially important on a private sale where you have fewer legal protections.
With a 79.5% pass rate and an average repair bill of £81 when things go wrong, budget accordingly.
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MOT data from DVSA anonymised test results, 2024 test year. Fleet data from DfT vehicle licensing statistics. Crown copyright, OGL v3.0. MOT pass rates are statistical summaries of test outcomes, not assessments of individual vehicle safety or condition. Always inspect a vehicle and check its full MOT history before purchasing. See terms of use.