Should I buy an SUV with a diesel particle filter?
I only do low kilometres with short runs to and from shops etc and I like the Hyundai Tucson with AWD. However, there's the diesel particulate filter issue. Can I own a diesel and do short trips?
You could also look at the Kia Sportage Platinum 2.4 petrol - same platform as the Hyundai Tucson >>, only different styling. Great engine and integration into the platform. See also Kia Sportage review >>
Diesel doesn’t mind short distances - but you do need to run occasionally on highway and free-flowing arterial roads at speeds of 60-80km/h plus to regenerate the filter. These runs need to be (say) 15 minutes or more in length, and ideally a total of one hour every month or so (minimum) would keep the filter healthy. If the filter gets a little clogged it throws up a warning light on the dash, which is an alert to either go for a freeway drive or visit a dealer (they can do a manual regen). Frankly, just go for a burn (literally) down the M4 once a fortnight, grab a coffee, then turn around and come back. People blow this operational requirement out of all proportion: It’s hardly the Iliad...
You mention in the Mazda CX-5 review that the particle filter can cause issues if it is not driven on highway once in a while. Could you please expand on what you mean by this? I assume you are saying it needs temperature to be built up to burn off things in the filter. I thought Mazda would have done a modification to fix it.
I also read somewhere about an issue with fuel seeping into oil in early model. I believe Mazda fixed this item. Is this correct?.
You also recommend looking at Tucson and Sportage. Does this recommendation refer to current model only or does it apply back to 2014 models.
Particle filters are storage facilities for soot. In some driving conditions (usually 60-80km/h plus, for periods of 5-15 minutes, plus, continuously) they turn into little furnaces and burn off the soot. This is a good thing. It's what they are designed to do.
Unfortunately, if you don’t do the driving described above for a minimum of about an hour each month, the burn-off does not happen, and this starts clogging the filter. If the warning light comes up on the dash, you either go for a drive highway drive promptly or go to a mechanic/dealership where they can manually regenerate the filter. If you don’t do that, the filter blocks, the car goes into ‘limp’ mode, and the filter may need to be replaced - for $4-7k, depending.
Mazda did have a problem with oil dilution in early CX-5 diesels - they fixed this with minor hardware and software changes to the early units as they came in for service. Oil dilution is a normal part of diesel engine operation, and it needs to be balanced against the diesel particle filter regeneration protocols. Basically they got the balance wrong in early units.
Previous generation Tucson & Sportage: Good SUVs generally - Kia did a better job on Sportage than Hyundai did on Tucson prior to current models.
More here: Mazda CX-5 Review >>