I have both 1.6 Altis 2017 (pre-facelift) and now a 1.8 cvt Grande 2018 (post-facelift). I am writing a rough estimate of the consumption ranges that I get which have been gathered from driving the 1.6 for a total of ~15000 kms and 1.8 ~8000 kms.
If driving in high traffic areas, the Grande gives better mileage (1.6 gives 9-11 km/l vs. 1.8 gives 9-13 km/l).
If driving on low-Traffic areas, again the Grande gives a better average (1.6 gives 12-14 km/l vs. 1.8 gives 13-21 km/l).
If on long route and driving at speeds greater than 140 km/hr, Grande gives better average (1.6 gives 12-12.5 km/l vs. 1.8 gives 13.3-13.8 km/l)
If you have an extremely light foot or an extremely heavy foot, can you guess which car gives a better avg.? Grande!
As far as driving or experience is concerned, it's a no-brainer that Grande is a much much better car. The only real issue is the extra Rs. ~4 Lac one has to dish out