For the more advanced crafting items, like vehicles, I am hoping you would need to craft a bunch of parts and once you have all of them you can craft the final item (vehicle, weapon, machine etc..). So say for a car, you need to craft four wheels, a frame, the motor, axles, suspension maybe.... that kind of thing. Once you have all those you put them together in a final car recipe.
Horses we can ride are planned I believe, so adding a wooden horse cart would be nice.
I didn't intend the go kart to be just recreational, although it should be fun. I mean why not? Would be foolish to make the vehicles in the game boring... IMO any vehicle in this game has a use other than fun. Like the car you mentioned Geneo, it takes you from A to B. Go kart does the same, but is much more simple to make then a car. And the go kart would be more dangerous then a car, so people would have more motivation to build a car, other than the car just being faster. To make the go kart more useful, maybe have a simple trailer that hooks onto it which you can load with stuff. This would help it replace the horse cart.
All of my suggestions, in any thread, are not intended to push the devs to add them ASAP. The suggestions are for whenever they get to it... when they get to vehicles, I would love for them to think about this idea. Simple as that.