How will you know? If someone manages to increase the efficiency of steam engines to 65 % for example, they'll be futuristic, because they're suddenly better than all diesel-, otto- or hydrogen-cell engines. Or may gyro-engines recieve a revival. Or there will be a kind of engine that does not exist yet. By the way, all the electric engines for cars or buses are extremely old, they just have a "revival" nowadays: This car is like a Tesla, just with electric motor, built in 1908, this bus from 1912, purely electric. May I should model it, it is swiss
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I don't think you completely understand the essence of futurism - which is, rather than to be futuristic in technology or design, the latter of which is not the case with many of these mods, but to portray something that will be deemed as such by contemporaries.
Your bus, for example, does not look futuristic. It does not look like any vehicle that will ever be made. It may be futuristic in concept, but it looks rather more like Duplo or Playmobil. The "Galaxy" bus, for example, is futuristic. And it's typically futuristic, by today's standards.
I'd even go as far as to say that your "Giruno" model from your train pack is more futuristic than either of your "futuristic" vehicles. And, by the way, that's a very nice model of a very good-looking train. So I wonder what your thinking was with your "futuristic" vehicles - especially considering you're always one Google Image search away from hundreds of actually futuristic designs.
