Below are my responses about your doubts:
1) Didn't here any noise from accelerator of my ZEST RT XT.
2) Experienced li'l bit of this at extreme end position of steering wheel.
3) Gear lever vibration occurs only if you push it 4-5 mm after sloting it. If you leave it there, no vibration.
4) Did you reset the trip meter before TD. If not, low mileage could be because of the existing KMs in the trip.
I expressed my concern about the mileage in the official facebook page of Tata Zest. The territory manager (West Bengal) called me and offered a mileage test. His offer was to fill the car upto autolock in front of me. Then I may drive the car for 30 to 40 kms and he will refill the car from the same fuel station upto autolock. So I can check the mileage with my driving habit. I was amazed with the offer and immediately accepted that. However, the actual scenario became different.
One SA from Lexus Motors, Kolkata came to my residence for the mileage test and told me that they already have filled the car in front of the territory manager. That was the first shock. The territory manager confirmed this to me over phone. I was allowed to drive for 10 kms only (the distance from my residence to the Lexus Motors showroom). Second shock. They now refilled the in front of me and the mileage was 10.43 kmpl with 100% AC, driven in city mode of a 1900 kms driven car. However, I do not know how the first 10 kms was driven.
The funny thing happened next. Third and the biggest shock. The SA asked me about the plans to get back to the residence. I was shocked. I told him that the TD was discussed to begin and end at my residence. But he simply denied. Then I call the territory manager again and now SA dropped me home.
Nobody asked to book the car, neither asked about the TD experience. I, personally, called the territory manager and told that I want to book the car. He forwarded my massage to the sales manager, Lexus Motors. The sales manager then called, heard my experience and told me that he will call me the next day. 12 days has already passed. No calls from anyone yet