24th Jul 2015, 21:55

Welcome the consequences of too much regulation. The diesel engine of yore was much, much more durable and reliable than a petrol car. But never mind trying to get more performance (turbo), to comply with all the ever-tightening emissions regulations, the diesel engine now has all sorts of components that are both consumable/replacement (diesel particulate filter/DPF) and very complicated (high-pressure injectors and pumps). Many items, developed to cope with a certain standard of regulations, haven't yet been perfected through years of actual usage experience, and are already obsolete for the next set of more stringent regulations - which may necessitate another new long-term unproven set of technologies.

Now here's the new problem: Petrol engines now, again to comply with newer emissions or CO2 regulations, are also getting more complicated. They're now using turbos (heaven knows if these use electronically-controlled variable vanes via a computer-controlled solenoid), and now often have direct injection (which uses high-pressure fuel pumps and computerised injectors - like the diesel). At least they don't have the DPF, but we'll have to see the long-term reliability and repair costs of these things.

25th Jul 2015, 11:12

I agree with your comment about regulation. I see now that's what is causing the problems, not the diesel engine itself. Too many environment issues, but that's understandable. Mind you, a petrol engine will still do in excess of 200,000 miles without any issue, and a modern diesel is expected to last even more. I did hear of a friend who used a Skoda Octavia as a taxi lasting to 500,000 miles, but it was the old generation without the DPF and DMF, so it was economically viable as a taxi. I guess the thing to consider when buying these cars is - am I really going to do the mileage to justify the savings in fuel economy vs. the repair costs? If not, I still stand by my comment that petrols are the better choice for lower mileage. Anyone I know with a petrol Mazda 6 has had no problems, but the diesels are to be avoided. Maybe it is just this particular car's diesel engine, I don't know.

Interestingly though, I considered a 2006 Ford Mondeo at one point, a petrol one, and was surprised to learn it had a DMF (dual mass flywheel) which I though only applied to diesels. Assuming it doesn't have a DPF (diesel particle filter) obviously though, petrols still use the good old catalytic converter (I hope!) which seems to last the length of the car. I still think manufacturers should do more to reduce these repair costs on these particular items, as it seems to be what's causing the biggest headache and high repair bills for people over the last 10 years or so.

26th Jul 2015, 19:34

You're correct about the Mondeo DMF - I was considering one years ago, used, but because they were fairly new (the 2001-2006 models), the clutches were a NZ$3K job, instead of something like $600-800 on a conventional 1990s vehicle, because of the DMF. Scared me right off it.

In saying that, my mate here has a 2002 ST V6 he's had since new (was his company car), he still has it as his main car, now done 210K km, still with the original clutch. So I guess also how you drive it helps, and I've heard lately that these clutches are now not as expensive to repair, possibly because the aftermarket has caught on.

My own personal car, a 2001 BMW 316ti, already has a DMF; my mechanic says that for this model, the DMF most often will not require replacing like the clutch itself.

I'm with you in thinking that, if these parts (DPF, DMF, electronic injectors) are to be commonplace out of legal necessity, they should be made more affordable. After all, what is the point of a 10-year body warranty and galvanised bodies, if the whole car is to be written off because it's too dear to fix? So much for being environmentally friendly, when you have to manufacture a whole new car to replace that one. I'm sure that for whatever minute improvement there is for emissions, the car and part manufacturing plants are actually not as clean in emissions as today's V6.

27th Jul 2015, 15:19

Agree 100% mate - here in the UK it's the same story. Nice choice of car, the 3-series BMW was always a good car. But what I like about cars such as the Mazda, Ford and Vauxhall (Holden in Aus/NZ) is that they make an affordable alternative to the likes of BMW and Mercedes and Audi. But as we have talked about, if the repair bills for these cars are getting more and more with every passing generation of them, what's the point? And I'm talking used of course. Not buying new, where I would expect any car to be perfect, since most of the cars I've had have been around 10 years old and high mileage, and have given me little problems.

I wrote the original review and a few comments on here, and looking back as I mentioned, the Mazda was a good car, but I'd never pay a premium for any diesel car again; it hasn't been worth it. The saving you make only amounts to a possible 900 - 1000 UK pounds on fuel anyway, so the way I see it, once you get such a repair bill, any saving has been cancelled out, unless you keep the car for another couple of years and it returns with trouble free motoring, but honestly it's unlikely with the mileage climbing. A used car is a used car, and I'll now always drive petrol, good reasonable mileage examples for around £1000 - £2000, and run them for a year or two.