ignition timing, tappet adjustment, can improve. fuel economy. For smoke in morning compression test can determine how much more engine can survive before an overhaul is required. - am not sure of WAH but in Haripur in close proximity of NRTC compound there is a proper workshop where NRTC send their cars for tune up & maintenance, you may try that place with only 1 complaint - high fuel consumption and low pickup wait & see how do those people respond & fix the issue