But that is the problem, isn't it? For example, the very good 1.6 Sigma engine in my 2015 4/4 does not comply with the latest EU emissions regulations. I believe the same applies to the Plus 4's engine. And they cannot simply drop new engines in...
I'm not sure whether the 1.6 Sigma engine does not comply or whether it has simply not been homolgated under the new rules. In any case it would not surprise me enormously to see it replaced by something of a smaller capacity with a turbo
It is, after all, the current trend and very few manufacturers now have naturally aspirated engines in their product lineup. If you were a small producer you would be looking for a supply of engines that are already homologated under the new rules.
I agree with all that and there are several efficient engines that would fit nicely into a Trad. But the problem is that the homologation process makes that difficult for small-scale car manufacturers. The MMC cannot just replace the Sigma engine with something else and get it rubber-stamped for next week.