Remedy for high consumption and vibrating engine
I am in Quetta and the quality of petrol is really low here, I've had this low mileage plus little long self problem twice. Once i serviced everything (you can find details in DIY section) and found an injector chocked (rectified it). This time i only used a cleaning agent easily available off the shelf, i was recommended to use MAG and WHIZ which i couldn't find and used ABRO (made in USA) instead.
Both the times i revived my fuel average, quick starting and stable idle. I'm getting 15+ in local running w/o AC but i do keep my foot a little heavy on accelerator pedal
this is the second time i am having a vitz new shape. Knockin is inharent in this model, using 25% high octane has always been helpful. In case you don't get high octane try running on an RPM where the knocking doesn't occur.
I don't think that CAt gets chocked so early, like under 100,000 km. In previous car i did replace it (details are available on PW, go through my profile and you'll find the thread explaining procedure). It is better to rule out other problems first, which may have caused knocking or vibrational effects. Even a visit to toyota motors will be more appropriate then fiddling with CAT on just a hunch.