I have been driving Zest XT Petrol for the last 4 months and have clocked~4000km. At the outset, I can assure any one that it is an excellent VFM. The cabin space is large enough. I am almost 6 ft tall and ingress and outgress is without any hassles. I am getting a mileage of almost 14.5 kmpl since last service. The mileage improved drastically after the first service. This is happening since the last tank full. I have used the Indian Oil xtraPremium and regular unleaded mixed in 2:1 since I was on highway and xtraPremium was not available on the petrol bunk where I stopped.
The gear lever has been notchy while changing gears. The service assistant lubricated the gear cables in the first service and since then the lever is very smooth. I can change from 3rd to 2nd using one finger while driving. The car is super silent inside. The NVH levels are low. The music system is awesome and my Zest is fitted with a navigation maps(supported by a smartphone app+ Harman infotainment system). The navigation map has made my travel to unknown places very comfortable. Alloy wheels, 15 inch bridgestone tyres, head light assembly and sturdy body makes the vehicle excellent to drive. Recently drove from Delhi to Jaipur and even after 5 hours of travel, neither my family nor I were fatigued or had any issue. Sitting in the back seat is quite comfortable. Though the quality of plastic is not the best when compared to the competition, but I can vouch safe that the overall build quality is possibly the best.
In the last 4 months, I have not faced any issue. People have to realize that they have to maintain any vehicle well, be it Tata or anyone else. Proper servicing, lubrication, cleaning, oil levels, filters etc should be done periodically. Tatas as such have free service camps every 3 months which does the basic checks. This is a great plus for any passenger vehicle.