Hello Brother, I own Mitsubishi EK-Wagon myself and I have only this car to drive so I've tested it in all conditions taking care of all parameters. I've been driving this car since December 2012 so I know every bit of it.
First of all please clear your mind that these JDMs will not give you fuel efficiency whatever the dealers say and whatever your perceptions are. I was also infected by the same arguments from the dealer that this JDMs (EK-Wagon) will give you round about 16-17 km/liter in city without AC and I believed him and bought but I only came to know once I drove this. Maine her tarah ki jugaaaar laraa liye hain but it is not giving me more than 14 km/liter in city without AC and 20 km/liter on motorway (without AC, 90 to 100 km/hour speed).
On Queens Road opposite to Jinnah Degree College there is FAW showroom, they are official Mitsubishi dealers as well as mechanics. I also consulted with them. Everybody is thief here and everybody will tell you their own stories and try to take hell much amount of money from your pocket. When I visited there, the mechanic told me to get its throttle body serviced (2500 Rs.), buy genuine air filter (2500 Rs.), buy genuine plugs (2250 Rs. 750 Rs. each), 1000 service charges. Once you will do this, only then we will be able to diagnose via computer where the problem is and why your car is consuming so much fuel? I literally abused the mechanic for all this ******** and I left his workshop immediately. O bhai agar 10000 Rs maine diagnostics se pahle hi lagaane hain to faida ...
Anyways, brother, my sincere advice to you is, get your car's throttle body serviced, air filter, oil filter, ac filter, plugs and catalyst convertor checked from a good mechanic. Please visit filter house Montgomery Road and ask them to give you air filter, oil filter. I use Liqui Molly, you can have your own. I go to Magic Moters in Model Town. You can go to your own but he should be intelligent enough to guide you.
After all these discussions, I am not trying to disappoint you but if possible please sell it and buy any good PKDM (Swift is little better than rest). I am also planning to sell my EK and buy Suzuki Swift. Rest is your decision.