Preventing full time residence in a vehicle from being the only viable option is not the same as forcing a sedentary playstyle, though it’s not unreasonable to read the current thread and come to that conclusion.
The intended outcome of making a stationary base viable is not to replace having one or more vehicles, but to make the typical playstyle involve both stationary bases and vehicles. If someone wants to restrict themselves to a “traveling light” playstyle, that should continue to be viable as well, as long as they can scavenge or buy the resources they need.
- Physical protection
Via a combination of nerfing vehicle carry weight, bulking up the capabilities of stationary defenses, and adding large-scale threats that move around on the map, we want to make a developed stationary base safer than most vehicles. When combined, this may lead to scenarios like setting up a fixed ambush location and then leading a horde or problematic monster to it with a vehicle.
- Resource production and crafting
Farming, heavy crafting, and large-scale item storage are all areas where stationary bases have capabilities unmatched by vehicles. As we further emphasize these strengths, it provides a reason to establish a stationary base for these purposes. Of special interest is fuel production. Setting aside super-science power sources, I find it hard to imagine building a functioning mobile base that contains all the gear necessary to survive long-term in essentially a wilderness plus means for self-repair and fuel production.
- NPC living spaces
Whether founded by the player or NPCs, settlements will tend to attract NPC to settle down in a way a lunatic in a deathmobile isn’t capable of. Groups of NPCs are specifically capable of mobilizing to perform tasks that should be impractical for the player, providing a source of mass manufacturing, resource production, skilled labor, and sometimes even firepower that the player is unable to bring to bear themselves.
Examples:
While mobile weapons platforms (tanks, APCs) exist that should be able to handle any threat the game throws at them, these vehicles are not capable of operating autonomously, and require a home base for storing excess items, repair parts, repair tools, fuel, ammunition, etc.
Large cargo-hauling vehicles also exist (i.e. an 18-wheeler or to a lesser extent a 6-wheeled cargo truck), but I anticipate balancing them to the point where using them as a daily scavenging vehicle is impractical due to high fuel use. OTOH, if you were to pack up a base and move to a new site, it should be feasible to scavenge one specifically to handle a move without having to shuttle back and forth.
I could imagine a mostly self-sufficient cargo bicycle capable of carrying the player, repair tools and spares for the bicycle, as well as supplies such as food, water, weapons etc, but this kind of setup would require constant scavenging to continue replacing items as they are expended.