@keisuke if it looks stupid but it works, it's not stupid.

Although I don't really think that this is an engine limitation tbh, I think it's just what they thought was going to be easiest to do. If they wanted to add vehicles to the game they certainly could have because they have access to the source code of the engine... But it wasn't necessary so they didn't do it. There are probably several different ways to get some janky vehicles in there anyway though, modders have already done it.

So saying it was an "engine limitation" is kinda BS. An engine limitation is more like when you're trying to work with something that is closed source and because the devs never implemented a certain feature there's just no way for you to utilize it. Modding, for instance, is like this. There are engines that are only 32-bit so the amount of shit you can do to the game is going to be capped by memory restrictions at some point, for example. Or maybe the devs just didn't need to use mip maps because all the maps are really small, so you can't make big open maps otherwise they'll lag like hell.