The car keeps troubling, you must have had heard that you need to adjust tappets.
In Corolla, And Vitz the tappets cannot be adjusted they need to be grinded.
My mechanic told me, after some time the engine valves (the one we hear 16 valve efi,) they need to be replaced, if proper maintainence is not done. or else the engine would die.
Carbon deposits choke the engine valves due to which they stop working and the entire load comes on the ones working.
All in all theres no tranny issue
The above written is what i my self understud as a layman. As i dont noe how the engine works.
How ever CVT transmission Honda City and Toyota Vitz Gen2 are considered flops on CNG.
Dunt noe much abt the VItz 2nd Gen, but in Honda City, a particular kind of voice starts come, and it is considered that the transmission is about die which would include high costs.
And another reason for this is the simple Automatic city, This time City is nor Vario nor Prosmatec its a simple Automatic.