Darkness Falls has vehicle mods but its done in a workaround way where its basically a new vehicle with improved stats, can't wait for it to be put in game though in a19 which I think was where they said it was coming, the groundwork is there already as the vehicles have slots already. I can see: Speed mods, inv size mods, gas tank mods, gas consumption mods, maybe armor mods (Why I dunno, its pretty damn hard to destroy the vehicles as is), maybe mods so they can climb hills easier, torque I think its called? I'd love a jump mod for the 4x4's front wheels so it doesn't get stuck on tiny hills. The bikes you can hit C to do a wheelie which helps you get up hills but the 4x4 doesn't have it, so its front often gets caught on things. I actually hate the 4x4 due to this and rarely use it, had one last game and going to 1 trader quest I had to get out and pick up my 4x4 4 times as it got stuck on terrain and I had no way to drive it out. Thankfully the truck was pretty much empty but if that happened on the way back from a loot run I would be very annoyed, as the 4x4 now has over double the inv space of the motorcycle. Due to this I generally stick to the minibike or motorcycle whichever I can get, less storage space than the 4x4, but never need to worry about getting stuck on things in A18 on them.