Changing car frequency

[peterfaj]

I'd like to change the possibilities of a car spawning in traffic. Like, you see a greenwood almost all the time and never an infernus, how do you change these frequencies?

In vehicle.ide there's something called frq flags that are always x,0,0. or x,0,xffx something. I've tried changine the first x to 10 but no visible change.

Searching on google, I've read that adding the name of a car into every line in cargp.dat should make it appear more often. But...it doesn't.

I'd like to make cars that never appear more frequent.