if it is just the level indicator then it is common with all EFI and even non EFI cars these days.
Anyway like I Said bro i am really not sure abot CNG coz there has been so much discussion on PW on CNG and it is like half of the people say dont go for CNG while the rest say it is OK.
Nevertheless if God forbid the CVT transmission is damaged coz of CNG then it is Rs. 100,000 expense to replace it.
I request other bros to comment on this as the dude wants to buy the car