Where do you guys get these cost numbers?!?
European aviation is insanely expensive. There's no such thing in Europe as economy in aviation.
Setting aside European aviation, in the real world, the 172 is very economical to operate.
As for making a comparison to a 180 hp 172, why not go for the XP? How about a 200 hp 172? It's a ridiculous comparison.
Most 172's are 150 or 160 hp, and they're very economical choices.
Bear in mind that in the US, an experimental airplane isn't allowed for use in flight instruction or rental, or commercial activities.
As for private pilot owners who fly 400 hours a year...not very many. Most pilots who fly that much, or more, do it for a living. Making cost comparisons based on several hundred hours a year is nonsensical and ridiculous, especially for a real-world comparison.