I did it using this guidance, but it doesn't work as it should.

All the zones at the moment of posting are:
parkingstall |Parking Stall, common parking stall with random cars, the most used one (shop parking lots, houses etc.)
trailerpark |Trailer Parks, have a chance to spawn burnt cars, some on top of each others, it's like a pile of junk cars
bad |Bad vehicles, moslty used in poor area, sometimes around pub etc.
medium |Medium vehicles, used in some of the good looking area, or in suburbs
good |Good vehicles, used in good looking area, they're meant to spawn only good cars, so they're on every good looking house.
sport |Sports vehicles, sometimes on good looking area.
junkyard |Junkyard, spawn damaged & burnt vehicles, less chance of finding keys but more cars. Also used for the random car crash.
trafficjamw
trafficjame
trafficjamn
trafficjams |Traffic jams by cardinal direction, mostly burnt car & damaged ones. Used either for hard coded big traffic jam or smaller random ones.
police |Police department vehicles
fire |Fire dept
ranger |Ranger police vehicle
mccoy |McCoy Lumber vehicles
postal |Postal (mail) vehicle
spiffo |Spiffo branded vehicle
ambulance |Ambulance
radio |Local radio station vehicle
fossoil |Fossoil branded vehicle
normalburnt
specialburnt |When spawning burnt vehicles for any zones, 20% will be pick in special burnt vehicles and 80% in the normal burnt vehicles list