After a series of breakdowns with my current car, I've finally decided that its time to get a replacement. Looking round local dealers, I've found a 9 year old used Mazda 6 diesel which seems to meet my requirements, and as far as I can tell is in pretty good condition (including most of the points mentioned at What to check when buying a used car?)

My concern though, is its very high mileage, with 198k on the clock, although it does seem to be priced to reflect this. As I've never owned a car with anything even close to that mileage before I wanted to ask the experts here whether this seems like a good plan and is there anything specific I should be checking over and above the normal checks?

  • Old high mileage diesel? Don't buy! Dual mass flywheels, diesel particulate filters, injectors, turbochargers, EGRs, ... The list of troubles is endless.
    – juhist
    Commented Aug 1, 2017 at 10:16
  • I bought a car with relatively high mileage and have added to it generously. A "low" mileage supermarket shopping car can be a worse purchase as it may never have been run warm etc It also depends heavily on the maintenance schedule high mileage with good maintenance can be a good option.
    – Solar Mike
    Commented Aug 1, 2017 at 10:42

2 Answers 2


That works out at 22k miles/year, which is about double the UK average. Given the type of vehicle, I'd surmise it's been a 'repmobile', so I'd hazard a guess that most of those miles have been slogging up and down the motorway from one meeting to another.

It's therefore probably been driven quite hard - so make sure it's been very well serviced. Check the history thoroughly. It was probably a lease car (I think most company cars are these days), so make sure the lease company looked after it - I doubt the driver would have done!

Have a look at the MOT history too - most company cars are replaced after three years, so it's likely that the mileage is biased towards the earlier part of it's life. If it had done 40k/year for the first few years, then much less since, you might find things that had worn during the first owner's tenure hadn't been dealt with by the next owner.

Personally, I'd leave it and go for something with a closer-to-average mileage, unless it's really cheap...

  • This "average UK mileage" so based on all people's use - those people who do 5 miles a week for shopping up to the salespeople doing 30k a year or more - is it a good measure?
    – Solar Mike
    Commented Aug 1, 2017 at 10:45

It's not an old car so I wouldn't be worried about rust yet, although it's definitely worth a look. Suspension, steering and brake parts are all replaceable, so if it's been maintained well mileage isn't really an issue there. My main concern would be with the engine.

Engines wear out no matter how well they are maintained, and high mileage is a good indicator of engine wear, even if it's been driven gently. Cams will no longer push rods as far as they should, valves will go out of tolerance, piston rings wear, gaskets break down etc. These problems will lead to other problems, and you could end up with some expensive bills. Cars with that mileage tend to nickel and dime you, it's often more economical to spend more money up front for something with less miles.

If the car has had a full engine overhaul with worn parts replaced, new rings, seals, gaskets, etc then it may be worth a shot as long as the rest of the car is primo, otherwise I'd pass on it.

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