hi everyone. my dad used my car when i was out of city for a couple of days. now when i'm using it i realized, my car is burning almost %20 more fuel on my everyday route. according to the reading of trip computer, car was burning 5.5liters/100km @70kph with cruise control. now i read 6.9-7.5. it differs even more when going uphill. it seems like having trouble with burning fuel?

also it sounds kinda different too. there is no obvious sound/rattle i can really say here but, it kinda sounds like pistons moving roughly inside the engine.

carbon buildup? hpfp? oil? pls help me.

09 mcs 65k km.

 

Any idea if he bought fuel?? Maybe low octane stuff out of habit?

 

yes, he bought some of the worst (coz' it's cheap) fuel here. but not much, just 10 liters or so. i burned it, and bought 10 liters shell's premium 95. but still same.