[ғαιιοцт]

change
CreateVehicle(592, x+4,y+4,z, a, -1, -1, -1);
to
CreateVehicle(592, x+4,y+4,z, a, -1, -1, 99999999);



or try
CreateVehicle(592, x+4,y+4,z, a, -1, -1, 0);
but I'm not sure if that works.

The last parameter is the respawn delay, in seconds.
https://sampwiki.blast.hk/wiki/CreateVehicle