Hi Manish.. Tata has come a long way from its first Indica ten years ago. They have learnt a lot and proof of this is the new Indica Vista. Your question is some what incomplete...
The Indica now comes in two variations
1) The New Tata Indica Vista with a fiat 1.1 Ltr Petrol engine, 1.4 ltr TDI Diesel engine and the rocking 1.3 Ltr Multijet (also used in Swift Diesel, Fiat Grande Punto, and Fiat Palio)
2) The Older Indica Xeta which comes with a 1.2 ltr Petrol engine and a 1.4 TD Diesel Engine.
All models have certains advantages and dis advantages, so the choice amongst them actually depends on your requirements.