Open your vehicles.IDE file with notepad in data directory of San Andreas.
You see the long list of all the vehicles in the game. Search which vehicles you want to spawn as traffic.
Lets do the quad, FBI Truck, and SWAT tank.
Skip down until u see the name "quad" scan to the right of it to the column called Class. In the class column of quad, it already says normal, so that's good. They column to right of Class is the FRQ column, or frequent. It's basically the frequency of the vehicles, how often does it spawn.
In this case, the quad has a 4 value for FRQ, change that to 10. Open your cargrp.DAT file with notepad. In this file, the list of the car groups are horizontal, from left to right. The title of the group is at the far right, or end of the group list. This is where is says which vehicles is driven by what group of ppl. Find the group called:
The last vehicles in that group should be petro, add a comma after petro and space once. write quad for the quad bike and make save. Done and donner.
Remember each vehicles has a certain codename, like Swat Tank has swatvan. Follow the same tutorial for fbitruck and swatvan as the quad. Remember, when a vehicle's class column says ignore instead of worker or normal, and you want it to spawn in traffic, erase it and type in one of the following:
-motorcycle (for motorbikes)
there's taxi if u feel creative and want the vehicles to be a taxi with a taxi driver and stuff.
If u want realistic, for dozer, for class type worker, frq as 10, put in
So u can put worker vehicles to spawn in worker areas and same for others.
Now to make your own gang drive around in rare cars or any car, make sure the car is already modified in vehciles.IDE file.
Now in cargrp.dat file and go down to (on right side) and go to Gang 2 column, your gang, now go to left of gang 2 and after voodoo add a comma, space once and type what car you want your gang to drive, I wrote quad tounge.gif You can add multiple new gang cars.
Sorry if a bit messy but im in a hurry. Any more questions, ask here.