Horns could be greatly useful (they were indeed at State of Decay, specially the Police Cruiser's siren). Imagine you need to clear a path for your friend to go and loot some stuff: You would just grab a car, honk like you're in a rush hour traffic jam and have all the zeds follow you like kids after an ice cream vendor. You don't even have to run over them, you just have to lure them away. Personally, in State of Decay, the fact you could run over almost ever zed, including the special infected sans the Big Bastard was quite a bit of a nerfing. Specially since cars didn't seem to use any fuel and could be stronger than tanks if you had a Machine Workshop in your base. Still, I hope we can door trip; that was perhaps the coolest feature of SoD's cars IMHO. All that aside, if cars get introduced, we should become able to use the Gas Stations to refuel them. At least until the power fails and we have to resort to stored gas. This could greatly help to avoid the cars from being overused. And also, if the Devs wanted to add a higher level of difficulty, maybe they could make the Gas Stations into self-service stations (just like that one in Highschool of the Dead), where you'd need money to get gas, money you'd had to get from cash registers, peoples' homes, other survivors or those now-useless wallets you find on dead zeds. Also, once cars get broken beyond usability, it'd be best if they don't just EXPLODE a la GTA fashion. There's plenty of useful stuff to be obtained from a car; Car batteries, Headlights, Horns, Seats, Tires, all that metal from the doors and hoods (could be used for barricading), even the engine itself could be made into a Generator if it still worked (I remember a generator made with a truck engine on Stalker: Clear Sky). So, to sum up, cars and vehicles would add all kind of new possibilities.