The Fuel Type of Indica Vista EV-X is listed as Electricity/Petrol, so it is a hybrid. Looks like Tata signs up EIG just to meet the criteria of X Prize. It is designed to meet the US market. Here are the criteria to quality for X Prize:

Production Capable Vehicles
Our goals require that PIAXP vehicles and vehicle modifications be designed to reach the
market. Accordingly, all vehicles entered into the PIAXP competition must be “production
capable”, as judged by expert panels in four areas:

• Safety, Emissions: Vehicles must be designed so that a production vehicle would likely be able to meet U.S. safety standards (FMVSS) and U.S. emissions standards (Tier II, Bin 5)

• Manufacturability, Cost: Vehicles must be capable of being manufactured in quantities of 10,000 per year, with vehicle production costs within levels consistent with historical examples of comparable vehicles

• Features: Vehicles must be desirable, addressing the most important features and factors consumers consider when purchasing an automobile

• Business Plan: There must be a credible plan to manufacture, sell, and service 10,000 vehicles (or conversions) per year by 2014. The plan must show that the national fuel infrastructure will support the vehicles, especially if any non-standard fuels or fueling-methods are to be used.

http://www.progressiveautoxprize.org/files/downloads/auto/PIAXP_Guidelines_V_1.0_20090110.pdf