According to mechanic reason for quick wear & tear of my engine was due to CNG. QQ engine really does not like CNG and overheats.
Breakdown of Rs.80k maintenance is as follows (in sequence):
front wheel bearings - Rs.2k ea.
clutch wire + greasing - Rs.1.2k (changed twice)
Head Gasket changed twice due to overheat - 3k ea. time
new radiator fan - 4k
alternator repair - 3k
new waterbody - Rs.4k
new rings put in at 55k approx 8k along with some other work
AC Gas leaked after 3yrs, Gas charging - 2k
Windscreen cracked (god knows how), new screen - 6k
Complete Engine overhaul @90k km - Rs.25k
Clutch plate/pressure plate - Rs.5k clutch bearing Rs.1.2k
oil pump repair - Rs.2.5k
bumpers + 2 piece denting/painting - 10k
AC Gas leaked in 4th yr, Gas charging+cleaning - 4k
Now i've removed CNG kit and driving only on petrol. Hope there are no further loses. Same could have happened in Mehran as well i guess but prolly would have cost less. But QQ drive/comfort much better than Mehran so it balances out.