getting a Tesla soon, but not prepared to give up the Kodiaq RS, currently at 80,000 km, faultless so far. most of my journeys are 15km or less, but for DPF health, i give it 20 mins of motorway time once a week. i realise variables abound, but how many more km of relatively trouble-free kms can i get out of the car ?

If you look after it and service it at all the proper intervals, then I'd suggest the engine will last a very long time.

 

Most issues with modern cars seem to be electrical or other systems.

For DPF if can become more problematic over time but if you are running on motorway once a week then it should be fine. Higher mileage dpfs do become more difficult to clear. 

Granted my experience is Ford rather than VAG, however I pretty much killed two TDI vehicles at only 50k to 60k miles by doing mostly <15 mile journeys.  Some combination of DPF, EGR, hoses, sensors, fuel vaporiser, etc.  I don't know if VAGs are fundamentally more reliable by I certainly wouldn’t ever take the risk again.

If it is winter in New Zealand, then 20 minutes of running  is not going to be enough to fully clear a DPF, really needs to be 20 minutes once it has already warmed through, so need to be doing at least 15 minutes (and in cold weather probably nearer 25 minutes) before you start the DPF regen.

 

You can shorten time by holding it in low gears, but running at about third of  maximum revs is not going to generate lots of engine heat quickly.