A few factors determine engine longevity, so let’s start with the first of those, the basic materials and design of the engine in question. Both the Toyota and Honda have advanced small-capacity engines that are made from quality materials. So that’s in their favour.
The second factor is servicing. A lack of regular maintenance including fresh oil and filters will kill engines fast, so that’s crucial. And finally, how they are driven will also play a part. An engine that only does long distances in the country will always last longer than one that is subjected to frequent cold starts and stop-start traffic. An engine that is regularly revved to redline between the gears will also potentially die younger than one that is driven sensibly and with a bit of mechanical sympathy.
The bottom line? There’s no short answer. But I have seen small-capacity Honda and Toyota engines clock up 250,000km and more with correct maintenance. Things have certainly changed from the 1950s when the average car engine needed a rebuilt every 100,000km and what was called a de-coke and valve-grind every 30,000km. Ask your grandfather about it.