Start with nodes and beams: https://wiki.beamng.com/Introduction_to_Vehicle_Creation You might not get away from Blender completely though, but you can really skip part about making body of vehicle, just make those nodes and beams first. Then you can of course model with Maya LT, Sketchup, 3ds Max, but again you need to learn those programs. Perhaps first step could be to make a simple prop, making just nodes and beams without any model, just to get used to how vehicles are build. Then maybe you could make new engine for existing vehicle, look this page for information https://wiki.beamng.com/Vehicle_Creation_Megapage Also check out this post, where I put more links for anyone new to modding BeamNG: https://www.beamng.com/threads/generic-shopping-cart.52762/#post-807754 Update: Here is one more link: https://www.beamng.com/threads/tutorials-index-list-of-useful-guides.51454/
draw it on paper plan it out like you would if you was making it in real life but then you modle it into blender
If you want an easier modeling program, try out Sketchup. It's easier to use (more limiting), but it exports to .dae
