I have heard a lot about the common issues of modern diesels - it is somewhat off putting, as some of the repairs are very expensive and can make MPG differences look rather small.

The trouble with studying failure stats is that it can cause intense risk aversion, which may then lead to spending several £K more to get a low-risk car. At your stated budget I fear you may need to take the plunge and use your skill and judgment looking for specimens with a good service history.

If the correct preventive maintenance has been followed, you have a good chance that the car in question will give you good service. You can compare the chances of expensive failure, but that happens to a minority of cars - most of them keep going if they have been looked after.

Of of the major problems with buying a second-hand modern diesel-engined car is that its future longevity/reliability is as much dependent upon how it was used (especially the last owner) as it was maintained/serviced, and unless you personally know the last onwer very well and trust them implicitly, it is not easy to get any or an accurate picture of how the car was used.

What I mean from that is that diesels do not like repeated short trips from cold, which will likely lead to cumulative damage to several systems (like the DPF) as mentioned by SLO earlier.

The annual mileage isn't much of a guranatee as how it was driven - it could just as easily be made up of lots of short trips from cold as it could be from less, but longer ones where the DPF passively regenerated, nor will you know if the owner had a bad habit (assuming they knew at all what was going on) of stopping the car during an active DPF regen, which is very bad for the unit.

With petrol-engined cars (at least the standard configurede ones), up until very recently (and still for some) there are far less conplex bits to go wrong that are significantly affected by the usage pattern than for a diesel equivalent.

You pay less for one, at the expense of some mpg (more so for cars over 10 years old), likely around the 20% - 30% mark, but the fuel is on average cheaper and, as SLO said, the likelyhood of problems all other things being equal is lower and the consequences far less of a strain on the bank balance.

For petrol-engined cars, I'd tend to go for the proven examples SLO has given (I've onwed, for example, a 2005-built Mazda3 1.6 petrol from new with [thus far] no issues of note).

The KIA C'eed and sister car the Hyundai i30 are decent cars, though if I recall some did have some underbody corrosion issues, but then the Mazda for example does on some (earlier examples mainly, mine's fine) have some rust issues around the wheel arches. At this age, condition and a good full service history (preferably with proof, e.g. lots of dealership receipts, etc, not just a service book which can easily be faked).

The Mazda and Ford are the best handling wise and cheapest to buy, the Civic and Auris the most reliable/hardy but more costly to buy/service (at a main dealer), the Civic 1.8 the nippiest in 1.8 form. As I said, condition and history etc is the key here.

If a car has had few, preferably one owner from new who has kept all the receipts and presents a well-looked after car then that may be the one to go for - say a retiree who is buying a replacement (because they can rather then because the car is giving them problems) or giving up driving, perhaps.

Worth having a check done on the battery or getting it changed in case it has been terminally damaged by a lack of use over the past 18 months due to the lockdowns. Luckily replacing such batteries on older cars is less of an expense than newer ones which would have hybrid systems as well.

Sometimes these cars do end up as PXes on garage forcourts, and in normal times at least, dealers like to get rid of them asap without needing for it to go to auction. At the moment with all the new car (component) shortages, the second-hand market is very bouyant and thus what you'd get for your £5k is a good bit less (or older) than a couple of years ago. It may also take longer to find what you want due to the significantly increased demand for second-hand cars at the moment.

If you can, best to make sure that you know what you want buy (where possible) test driving some, getting to know the interior, driving position, etc. Not always easy for older second hand cars, especially at the moment.

It may mean some 'window shopping' - i.e. pretending to be a genuine buyer but are really interested - at first - to get a good perspective on what driving a particular model would be like - driving experience, comfort, etc. You can always say that you're checking several cars over a week or two to compare them - it's sort of the honest truth.

I would try and narrow it down to 2 or 3 models of car and then do as thorough checks/sit-in/test drive of them to see which is bast, then find the best but affordable examples you can, but don't just jump at something because there's not much in your area, at least not before checking its history and condition.

Edited by Engineer Andy on 15/11/2021 at 17:29

Edited by SLO76 on 13/11/2021 at 17:05