[Goldilox]

This might not be correct, but you can get idea how to make it.

pawn Код:

CMD:vehtext(playerid,params[])
{
new text;
if(sscanf(params,"s",text)) return SendClientMessage(playerid,0xCCCCCCAA,"/vehtext [text]");
new myobject = //create the object
    SetObjectMaterialText(myobject,text, 0, OBJECT_MATERIAL_SIZE_256x128,\
    "Arial", 28, 0, 0xFFFF8200, 0xFF000000, OBJECT_MATERIAL_TEXT_ALIGN_CENTER);
}

(Got reference from https://sampwiki.blast.hk/wiki/SetObjectMaterialText)