Putting a lower powered 1.0 three cylinder non-turbo, or turbo'd engine into even larger and heavier vehicles certainly wont extended the engine's potential for longevity and whilst it will be OPK for short trips very noticeable carrying a family of four about on longer trips if you are one that likes to get their foot down a bit. My wife is looking to replace the Fabia, she lost confidence in it many moons back, surprising to many here I would sooner she kept it longer, to get some return on the money spent on it sorting out its issues, but there are plenty of good used alternatives about (with much longer warranties than VW give) just that everyone wants them so prices are high for them, but then the Fabia remains overvalued too. Another option is to buy an older car with simpler stuff on the engine and none or far less of the electronic entertainments and "assists" and "aids" to go wrong fitted to the car. Perhaps an old petrol Octavia or even older diesel Octavia without DPF if they existed or another manufacturer's model without DPF. TSI is direct injection and known to carbon up but to be fair my wife's 2015, 1.2 TSI (90PS) 4-cylinder engine that so far averages around 7k-miles a year with many journeys of 2 miles still goes well but I have not looked inside to see what the carbon situation is. Last couple of years she has got into the habit of occasionally filling the petrol tank with a higher octane fuel just to get the extra cleaning additive package the higher octane petrol contains - and of course the engine gets regular servicing - good quality engine oil and filter, engine air filter and spark plugs. Good luck.