mmm... urs really suck...
maybe i can share my experience with my friend who own iswara...
i borrow his car and drive to Melaka from Kajang..
n guess what... I need to fill RM30~40 just to get there but my persona need around RM15~20..

so open the hood n check the head found out leak....
no wonder it drink a lot.. the engine pressure become low due leak so power reduce n i press more to get power..

so maybe u can check the head.. maybe u can find leakage at that area..