I have been using the Grand i10 nios Manual (Magna) for 9 months now. It is a really good car. The engine is very refined. Inside the cabin, it is very good. The seats are good. Steering and dashboard everything is good.
From a performance perspective, Steering is super smooth and road view is good. Ground clearance is ample (initially I was apprehensive). Safety is better than Maruti for sure. The build quality is decent.
Service is good.
Finally the mileage. I had having least expectations before buying the car and was a bit apprehensive (was using an alto before).
Highway mileage in mild AC and speeds 80-100 ---> 19 / 20 kmpl.
Low traffic outskirts type mileage -- 15 - 17 kmpl
High traffic city peak hours -- 11-14 kmpl.
It all depends on traffic conditions and how we drive as well. This is purely for MT Nios (which I have).