[Pinguinn]

Added a few things
I've set the 'vehid' to 400 (model id starts with 400)
Added a check to see if the model id is more than 400 and less than 611 (model id ends at 611)

pawn Code:

/* new vehid; // at top of the script if you are using it global */

if(!strcmp(cmdtext, "/pirmyn", true))
{
        new vehid;
        if(vehid >= 400 && vehid <= 611)
        {
            vehid = 400;
            DestroyVehicle(vehic[vehid]);
            vehid++;
            vehic[vehid] = CreateVehicle(400,-1954.6177,260.2105,35.5101,33.9648,0,0,-1); // vehicles start with 400
        }
        else
        {
            vehid = 400;
        }
        return 1;
}