All generations and engines together · 49,574 MOT tests in the 2025 data · typical mileage at age 7: 67k
Better than most SUVs, by age and by mileage. Watch emissions/leaks and corrosion. A solid used buy, provided its MOT history has no repeating emissions/leaks advisories.
Split by first-registration year. Cars registered in a changeover year can belong to either generation.
Owner folklore from forums and the motoring press, with how well each report stands up. Most of it never shows up in an MOT, which is why this section exists at all.
Early ML350 petrol models (roughly 2005-2007, W164) use the M272 V6, which is prone to premature wear of the balance shaft gears. It shows up as a rattle or knock from the front of the engine, usually between 60,000 and 80,000 miles, and left alone it can take the timing chain and camshafts with it. There was no UK recall, but Mercedes-Benz USA settled a class action over the fault in 2015, covering part of owners' repair costs, which is about as close to an admission as this generation gets.
Owners across all three generations (W164, W166, W167) report the car sitting noticeably lower on one corner after standing overnight, or the compressor running constantly and eventually burning out. It is a wear item rather than a design defect Mercedes has ever formally acknowledged, but it is one of the most repeated threads on the owners' forums. A single strut or the compressor is a meaningful bill; needing more than one corner done at once is not unusual on a tired car.
The M276 V6 fitted to ML350/GLE350 petrol models has a plastic-bodied water pump that owners and forum members report failing or weeping coolant, sometimes alongside oil seeping past the throttle body hose. This lines up with the measured MOT signature for this segment, which flags emissions and leaks as the standout fault category for large SUVs generally; a coolant or oil leak of this kind would not usually fail an MOT on its own but is exactly the sort of wear the data is picking up under the wider bonnet.
On the OM642 diesel (250d/350d/BlueTEC), carbon builds up in the intake and EGR valve over time, showing as rough idle, hesitation or a warning light, and owners describe stripping the intake for a manual clean as a fairly routine job by 80-100k miles. Separately, the AdBlue/DEF system on later diesels can throw faults that limit engine power or block a restart if ignored. Neither issue applies to petrol GLE/ML models.
Some W166 owners report the 7G-Tronic automatic being intermittently slow or unwilling to move out of Park, or a delay before the first gear engages from cold. It is not a universal fault and Mercedes has not issued a TSB that owners point to, but it comes up often enough on the forums to be worth checking on a test drive rather than dismissing as one bad car.
The first-generation M-Class (late 1990s to early 2000s) earned a reputation for cheap-feeling trim, rattles and creaks, badly enough that Mercedes reportedly spent hundreds of millions of dollars overhauling the Alabama plant before the second generation arrived. Owners of later, facelifted W163 cars argue quality had already improved by then, so how much this still matters depends heavily on the exact build date, which makes it a genuine judgement call rather than a settled fault.
Ranked from this model’s own MOT record, then from what owners report.
Saveable checklistThe physical checks its own defect data says are worth your time, most telling first.
These judge the seller’s upkeep rather than the model, and they are where the haggling money is.
The physical checks its own defect data says are worth your time, most telling first.
These judge the seller’s upkeep rather than the model, and they are where the haggling money is.
The physical checks its own defect data says are worth your time, most telling first.
These judge the seller’s upkeep rather than the model, and they are where the haggling money is.
The physical checks its own defect data says are worth your time, most telling first.
These judge the seller’s upkeep rather than the model, and they are where the haggling money is.
Drawn from the reports above rather than the MOT data. These are the model-specific ones.
Computed from DVSA MOT results, all of Great Britain, 2025. Nothing here is opinion.
Share of tests where each item was recorded. The dark tick is the class average across all tracked models; bars are scaled within each group.
The rows that judge the model rather than its keeper. 19,096 tests in this band.
Tyres, pads and stone chips say more about how the car was driven and maintained than about how it was built.
Same segment (Family & large SUVs), best MOT record first. Compare before you shortlist.