Hi there, I just tried it out, "prop_vehicle_sin" isnt a valid console command to spawn the car in the game, Im not sure what is in sin, since "impulse 82" (HL2's command) didnt work.
As for the Quadralex, the grunts seem to shoot at it even without the "ai_relationship" set, and setting it dosnt do anything, it only seems to react to the player, for example, when I set its ai to friends with the player, it just stood there and took the hits from the grunts.
As for how the syntax goes for them, its quite easy really,
Name: you can leave blank, unless you need to change the relationship mid game.
Subject: The thing that is having the AI changed, and you can put in the names you used for your npc's or use the class names ("npc_druglab_grunt_pistol") and it will then affect all of the npc's of that kind.
Target: The target of the relationship change ("!player" to change relationship with player) or "npc_quadralex" to change their relationship towards the quadralex
Disposition: How they feel about the target (options are self explanitory)
Radius: if you only want it to be in affect in a certain section, change this value, (I think it goes by units from the origin of the entity, dont quote me though)
Priority: Havnt used it, but I think it means, if they are in a room with two enemy types they hate, they go after the one with a higher hate priority first (again dont quote me)
Start active: do you want it to be on/off when map loads
Reciprocal: Does the target have the same relationship with the Subject
As for the Wiki, I think its gone, since Ritual is gone, I wonder if we can just add a "Sin Episodes" Section to the valve developer wiki, since thats not goin anywhere, and they got a section for "The Ship" which isnt a valve game. And sin does also use the Source engine, so its not totally crazy, I might look into it some...