Update:
sorry for the delays.
We had a Drive to Velankanni(in TN) two weeks back.A total of 1140kms and some 30%(:S) run was with A/C ON.Speeds where above 80kmph to 120kmph except for Hills(I took Kumali Route NH220 to save from maddening Kerala traffic).Overall Mileage is 20.67 .Car behaved Well all over through the drive.Don't Know Whether I need to give breaks on long drives.Drive almost 250kms in One Stretch without Breaks.
Once Turbo Kicked in ,It is plain Fun.
I had the Car "Running-in"(<60 to <70kmph) done for the First 2000kms with Oil and Filter Changed at 1000kms odo.
My Observations regarding Fuel Efficiency of Vista is ,This Car Will Give above 16kmpl in Traffic Conditions with sometimes A/C ON.While on a Free Highway ,Driving at 70-80kmph will give 20-22kmpl Mileage.
^^^ Don't take this too Seriously.These are all My Casual Observations.
And on Last Wednesday ,I went to Coimbatore(Bharathiar University) a total of 400kms.Car as usual ,was Fun To drive .This Time Mileage is Lesser ,I guess.somewhere around 20kmpl since 90% of the Journey I have to Put A/C in the Hot,Humid Palakkad-Thrissur sections of NH47.A/C Cools Fine-This is My Observation.But ,I need to put Blower on "4th" Position(5th is the Highest) so that Rear Passengers Gets A/C Effective.Any Idea If I fix a Fan on the Side Will Help Rear Passenger Cabin get Cooled Faster?
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Another Observation - Turbos Costs High and if not Idled for ~1 minute(I do this Whenever Possible) may reduce it's Life.
So ,Why Not TATAs and Others bring
TURBO TIMER's in India?Will Cost 5-6K More?(in a mass produced car).
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4000kms almost Completing and There is No Rattles as of Yet.
Waiting for 2nd Free Service.Will Update.