ATV Blueprint
To unlock the ATV blueprint, you need to be level 18 and must have 2 Craft Points available. You will need 25 Iron Bards, 10 Pine Planks, 15 Wiring, 15 Bolts and 10 Duct Tapes to craft the blueprint. After you craft the ATV blueprint you need a 3x3 area of level 3 floors to begin assembly. You can only assemble 1 ATV.
ATV Assembly
After crafting the ATV blueprint, you can proceed to assembly phase. To finish the ATV you need to painstakingly collect 320 Bolts, 100 Ball Bearings, 1 ATV Transmission, 1 ATV Gas Tank, 250 Thick Fabrics, 500 Scrap Metals, 150 Rubber Parts, 16 ATV Wheels, 120 Wiring and 200 Engine Parts. While it is impossible to complete the ATV at this moment, it is still prudent to collect all the available materials. So that, when the ATV Transmission becomes available, you can instantly complete it.
ATV Use
Since ATV Transmission is still unavailable in the game, I cannot yet determine how to use the ATV or ascertain it's features. Hopefully, the wait will not be that long.