DPF equipped diesels are ok if you are aware of how they function. I have a Kia Sportage 1.7crdi and knew about the issues when i bought it nearly 4 years ago. It doesn't matter whether the car does mainly short journeys as long as you know when a regen is taking place. The problems arise when the engine is stopped during a regen so its not allowed to complete it. I have the app Car Scanner on my i phone connected to a plug in OBD2 reader. Car scanner shows the soot level in the DPF and the miles since the last regen. When the soot level reaches 15g to 16 grams the regen starts and this is usually about every 160 miles. The soot level doesn't seem to accumulate any faster whether the car is driven on local runs or a fast one. Car scanner also indicates the regen is taking place because the exhaust temperature rises to 700c. A run of about 12 miles clears the soot to zero and then i know it's another 160 miles until the next one. Sound a faff monitoring this but petrol Sportages aren't known for being particularly economical. When posters say that diesels are more suited to higher mileages is probably true to a certain extent only because the chances of completed regens are more likely.
The soot should accumulate faster if you predominantly do short runs from cold rather than longer runs, because you get far more complete combustion on the latter.
The passive regen is then done on a long run (probably on a high speed road like a motorway) where the DPF/exhaust gets up to a reaonable temperature to burn off the soot and get rid of it via the exhaust, just at a slower rate than an active or forced regen, which is only done when there is enough soot in the DPF to start causing problems with the exhaust flow resistance, and thus affect the output of the engine.
Mainly doing short runs from cold with a very occasional longer run won't make much of a difference because it's likely that a good deal of soot would have built up on the short runs and any passive regenning won't burn off that much compared to an active regen, which is at a higher temperature and is presumably designed to get rid of far more significant deposits in the DPF.
Surely a well-designed diesel engined car used predominantly for longer runs should rarely need any active regens - certainly not every 160 miles, which is why they should be bought for that type of use rather than petrol-engined cars, which are more suited to shorter runs, but have improved their mpg enough to move the needle on changing from one to the other by (my guess) 5000 miles pa. Obviously ability to tow still rests with diesels for the very most part.
The previous Sportage is a bigger / heavier and higher sided SUV than its Ceed (what the OP is looking at) cousin, and is likley far better suited to turbo diesel and petrol engines than those previous designed non turbo petrols they used to have - which weren't that well regarded, especially on performance / mpg. The turbo petrols seem to be a decent improvement, although still behind the best that VAG and others currently offer, though the gap is narrowing.
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