Here are some of the specs that have been revealed so far (all relative to the smallest car as of today, Maruti 800)
25% more room space than Maruti 800.
7% lesser by length than Maruti 800.
20 KMPL mileage (this should send folks running to TATA showrooms)
Has passed the front and rear crash tests.
confirms to all international emission standards (EURO II/III etc).