carpeep

Mercedes-Benz 300, Buying guide, MOT record and UK numbers

2,897 Mercedes-Benz 300s are licensed in the UK. In 2025 they passed 78.2% of initial MOT tests, 5.9 points above the 72.3% UK average.

Looking at a specific 300? Check its finance, write-off, stolen, mileage and keeper history. £15, no account needed.

Mercedes-Benz 300 at the MOT

78.2% of 2,645 initial tests passed in 2025, ranking the 300 224th of 575 models.

First-time pass rate, 2025

Share of initial tests passed, retests excluded.

  • Mercedes-Benz 30078.2%
  • All Mercedes-Benz modelsThe 300 is 1.1 pts ahead77.1%
  • All cars72.3%

Where 300s fail

Share of all failure items recorded on Mercedes-Benz 300 tests in 2025.

  • Lamps, reflectors and electrical equipment29.7%
  • Brakes18.9%
  • Suspension15.3%
  • Body, chassis, structure10.7%
  • Visibility7.9%

The items testers recorded most often were headlamp aim too low (4.5%), ball joint dust cover no longer prevents the ingress of dirt (3.7%) and component mounting prescribed area excessively corroded significantly reducing structural strength (3.6%).

The MOT page lists every common 300 MOT failure. For one car's own results and advisories, run a free MOT history check.

Full Mercedes-Benz 300 MOT record

What to look at on a viewing

The 300's most common failure areas, and what a tester checks in each.

  1. Lamps, reflectors and electrical equipment

    Walk round with every light on: headlights, brake lights, indicators, fog lights and the number plate lamp. Check no warning lights stay on after starting.29.7% of 300 failure items

  2. Brakes

    Make sure the pedal feels firm, the car stops in a straight line, the handbrake holds on a slope and no brake warning light is showing.18.9% of 300 failure items

  3. Suspension

    Listen for knocks over bumps, check the car sits level, and look for leaking shock absorbers and split rubber gaiters.15.3% of 300 failure items

Mercedes-Benz 300s in the UK

2,897 were licensed at the end of June 2026. The number licensed has fallen 49% since the end of 2014.

Change since 2014
−49%from 5,718 licensed
Declared off the road
5,46465% of those registered, under SORN

Licensed Mercedes-Benz 300s since 2014

Licensed at each year end and in the latest quarter.

Show the figures
DateLicensed
End of 20145,718
End of 20155,306
End of 20164,915
End of 20174,579
End of 20184,216
End of 20193,856
End of 20203,477
End of 20213,383
End of 20223,118
End of 20232,800
End of 20242,648
End of 20252,538
End of June 20262,897

300 engines and fuel

3.0 litre engines made up 98% of Mercedes-Benz 300 MOT tests in 2025. Petrol accounts for 84% of licensed 300s and diesel for 16%.

Fuel type, licensed 300s

DfT licensing statistics, June 2026.

FuelLicensedShare
Petrol2,42084%
Diesel46916%
Battery electric1<0.1%
Hybrid electric1<0.1%
Gas60.2%

Other Mercedes-Benz models

The most-tested Mercedes-Benz models in 2025, against the 300's 78.2% MOT pass rate.

All 35 Mercedes-Benz models

Mercedes-Benz 300 FAQs

How many Mercedes-Benz 300s are there in the UK?

2,897 Mercedes-Benz 300s were licensed in the UK at the end of June 2026, with a further 5,464 declared off the road (SORN), according to DfT vehicle licensing statistics.

Is the Mercedes-Benz 300 reliable?

MOT data does not measure reliability. It records whether a car met the roadworthiness standard on the day of its test. What it does show is a 78.2% first-time pass rate for the Mercedes-Benz 300 across 2,645 tests in 2025, above the 72.3% average for all cars.

What should I check before buying a used Mercedes-Benz 300?

On the car itself, start with the areas it most often fails on: lamps, reflectors and electrical equipment, brakes and suspension. Then check the individual car's own records. Outstanding finance, insurance write-offs and police stolen markers are not part of the MOT record, so they take a history check.

How do I check a Mercedes-Benz 300's history?

Enter the registration of the specific car. A Carpeep car history check reports outstanding finance, write-off category, stolen markers, mileage history, previous keepers, MOT and tax status, import and export markers and scrapped status in one £15 report.

Already found a 300?

Check its finance, write-off, theft, mileage and keeper history with a £15 vehicle history report.

Across the 1,389 vehicles of every make Carpeep has checked since November 2025, 19% had outstanding finance recorded and 13% an insurance write-off. More on the Mercedes-Benz history check. To confirm a car's identity, see the Mercedes-Benz VIN check.

  • Outstanding finance
  • Write-off records
  • Stolen markers
  • Mileage history
  • Previous keepers

MOT figures are aggregated from the DVSA MOT Anonymised data set for 2025 (class 4 initial tests, retests excluded), which also gives the engine sizes. Licensed, SORN, fuel and registration figures are from the Department for Transport vehicle licensing statistics (VEH0120, VEH0124, VEH0160). Government data is used under the Open Government Licence v3.0. MOT results describe roadworthiness at test, not mechanical reliability. History-check findings are anonymous counts from reports bought on Carpeep, each vehicle counted once, and are published only where at least 100 vehicles returned an answer.