Hi Dave,

No production-car engine has a set point at which it requires a rebuild, if it ever needs such a thing, and so it depends on a number of factors as to whether this will be necessary for you. That mileage on a seven-year-old diesel Focus suggests it is a company car that has done plenty of distance each year, which means almost certainly most of its driving has been on the motorway – the best possible news for you, as a potential buyer. Motorway driving is very low-stress on modern, turbocharged engines like these and so this should be a reliable car. As a diesel, you need to check for any excessive white smoke during cold start-up or during hard acceleration, which might indicate a worn turbo (cheaper to fix than an engine rebuild, but still not inexpensive) and also check for any black smoke, rough running or an uneven idle – as these could indicate a blocked Diesel Particulate Filter (DPF), which (again) can be a costly fix.