Civic was a worldwide model, while City was mainly for developing markets. The after-sales support and part availability of Civic is marginally better.
Maintenance cost of both cars is fairly similar - however, a well-maintained City will always have better fuel economy than the older D-series motor Civic.
As for fuel economy, expect around 10-11 km/l on the Civic. 12-13 is doable, but you'll need to stay under 2k RPM. I have personally done 21 km/l on my own prosmatec once (stock D16W9), but that required advanced hypermiling on my part. It averages 10 km/l with normal driving.
Btw it's hard to find a 7th gen Civic nowadays with their stock engines - people tend to swap D15's or D17's without the proper wiring - you'll have to look hard to find one in a decent condition even in the 10 lac range.
