Drop the Misc Item, named "A Truck Spawn Marker", from your inventory and follow the directions it gives you.

-The "Panic Truck!" option is the original (and mostly defunct), swivel steering truck. Full control instructions are in-game, shown when built.
-The "Alarm Truck!" option is new rack and pinion steering. These are likely going to be the main setup moving forward.
-The "Build A Marble...?" option is just a silly giant marble. The arrow inside points in the direction it is facing. But good luck trying to control it...the arrow, as it turns out, is really no help at all...in fact, the arrow is almost evil in how it mocks you with its swiveling swivel of evil'ly evil evil'ness, lol.

Feel free to also try the:

-It all is what it is, a "proof of concept". Keep your expectations low. 'This is not New Vegas XRE', lmao!
I'm honestly just happy it "works" as well as it does and, to me and mine, it "works" better than I'd expected by quite a bit. ¯\_(ツ)_/¯
However, I will totally say it would probably be at least a little helpful if there was much less clutter/junk strewn about the Commonwealth roads though...and better roads overall, yeah...heh.

-This is a bit of a continuation of Wasteland Wagons. Check that out.

-Do not uninstall the mod while driving a vehicle. If you've uninstalled this mod before exiting the vehicle and caused your character to become frozen, hit the Tab Key, should fix it. But, as a mod user, you really should know better than to do that in the first place.

-Do not load a previous save while driving a vehicle. But if you do and this has caused your character to become frozen, close the game completely reopen it (don't just lazy Quit To Main Menu). But, as a mod user, you really should know better than to do that in the first place.

-You cannot be damaged while controlling the things. In fact, enemies will sometimes ignore you completely while controlling.
However, it is preferable to Exit the vehicle on somewhat flat land...as there is a short fall when dismounting.
It is what it is.

-The additional ESL file included, in the main download, is optional to enable. It is a patch to enable the things to collide with the player/NPCs. I decided to keep that separate because it edits vanilla records (Collision Layers).

-Built for keyboard/mouse. Anyone who wants to try to patch it for GamePad/Controller, please feel free to ask if can post a patch. Almost positive we'd give full approval, since I know quite a few people who would appreciate gamepad/controller functionality.

-Mainly for 3rd-person view. There is 1st-person view, but it is very jittery.

-If turn radius is a little wide, try getting out and back in or destroying the vehicle and placing another to use. Regardless, looking at this more.

-Turning is a little sluggish/slow to respond, working on that (again).

-Started adding in weapons. Very basic setup (though a few have unique ones and a few don't have any weapon at all, but most have an exploding cannonball). Will probably flesh that out later with, if at the very least, some kind of mounted ""weapon""'ish looking thing so the projectiles aren't just spawning from 'the ether'. Anyhoo, press the 5 key to lob projectiles in front of the vehicle.

-Your character is not seen on the main trucks for now. You can try the "Experimental Truck' (see notes above).
Hopefully, one day, will get a nice idle to work and translation to work quicker than it does in vanilla and lalala else-what that needs to be done to get that going.
If anyone wants to take that part on/provide (and volunteer the labor to set it up, like heavy F4SE/DLL type stuff), we'd welcome the assistance.

-It not supposed super fast...that's not what it's for, nor is it the point.
If a person constantly leans on the W key (or the Shift key), especially downhill, the person is just being silly or has entirely missed the point of this.

-This is a proof of concept.
Although, we do feel that it works well enough to stay in your game long term if you choose (but we won't mind if you don't after you've tried it).

-Started adding sound setup. I don't play with sound myself, so this is anh pfft meh whatever. Even so, got a SUPER basic set of sounds going right now. However, due to that and that people also just might not like any sounds at all, can adjust (from loud to all the way off) the engine volume with the number 3 key.

-They haz teh headlights! Press 5 key to toggle.

-Some vehicles have extra available colors/textures, which can be accessed from the LooksMenu of the vehicle (only if that particular vehicle has any optional colors, of course).

-They all go <poof> (eg; delete themselves) on loading a save. This is intentional and done for performance reasons.
And, since you always have the builder thing in your Misc inventory, you can always build new ones.
Additionally, they all share the same storage compartment/container, so if you destroy/lose one you can just build another to access their storage.

-Requires F4SE.

-Havok and low-FPS-potatoes do not play well together. Also it doesn't like people who turned off VSync (though goodness knows for what good reason they would have turned it off for to begin with. SMH my head).

-The silly little "EXPLOSION" explosion, when choose to put away a vehicle, is absolutely intentional, heh.

-You *will* flip over and/or get stuck sometimes. There are buttons/keys to press to try to help with that when it happens. If you forget which keys do what, press the number 4 key while riding (NOT numpad 4, regular 4 at the top of your keyboard).

-Save early, save often. As in before you get in, as you can't save while in a vehicle. Also, don't try to load a previous save while in a vehicle but if you do and gete stuck, close the game completely and reopen it to load your intended save.

-There is an optional file in the Files section, with some copies of worldspaces to goof around in (the worldspaces have lots of holes and floaty things, so really just for testing and goofing off).

-Truly, honestly, 4 realz, don't stand under a falling marble (or, any other vehicle really)!

-There is a random crash...can't pin it down...since this is all still WIP and 'proof of concept's, I'm not terribly worried about it at the moment. But, basically, the vehicle (super uncommonly and random'ly) unloads while still driving it and the game doesn't like when the thing the game camera is focused unloads so...<crash>.

-Imma say it once more, just for good measure. It is what it is. Think not about what it should be or should do, please think about what it is and does do instead.