https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1583079240

Nice that you also want to contribute to the MudRunner community and are interested in the editor!

If you are looking for some help related to the editor and self-created stuff (rather maps than vehicles), then The Big Book of MudRunner Map Making is probably the best documentation and guide available to date.
There's a very good chance that this guide covers what you're searching for and therefore will help you. There is a chapter titled Dealing with Editor Errors that might be helpful, but it's best to take your time and go through it all.

However, since the editor can throw a lot of error messages at you, SpintiresMod[stmods.org] might also be an idea.
Among many other improvements (like adressing more than 2GB), no error messages are displayed and only written to the log instead with this mod tool.

btw. SpintiresMod requires Visual C++ Redistributable Runtimes version 2013. Please note - both x86/x64 versions can be installed in parallel. I've not tested the current version of SpintiresMod (v 1.14.4), but with v.1.12.9 the runtime can be found in its installation path: ...\SpintiresMod\_CommonRedist\vcredist\2013 (it won't be installed automatically, and I think it will be the same as with 1.14.4).

However, there is a known problem, where mods cause crashes in multiplayer mode using SpintiresMod.