Seriously, this is up there with One Laptop Per Child.
By putting a new, efficient, CLEAN car into the reach of used car buyers, in a single stroke Tata has just ensured that tens, and maybe hundreds of thousands of inefficient dirty old clunkers will be taken off Indian roads each year and recycled into something better. And these will also be taking thousands of incredibly dirty 2-stroke scooters and bikes off the road as well.
Expect air quality to measurably improve in Indian cities (and the cities of any other developing country they end up being exported to) thanks entirely to these cars.