Is Tata Nano the most fuel efficient car?

Tata Nano is THE most fuel efficient car in India.

Automobile Research Association of India has given its confirmation that Tata Nano is now the country’s most fuel efficient car.
Maruti A-Star is now on the second spot. Maruti Alto and Hyundai i10 are at the third spot.
Maruti has been leading the charts for years now with their highly efficient models.
Tata Nano has crashed that party with its small size and highly optimized design which is designed to be efficient.
These ranks are for the petrol engine powered cars.
In terms of diesel… Hyundai Verna is the most fuel efficient model. Tata Indigo Dicor comes second.
Source:http://news.techwhack.com/10159-tata-nano-fuel-efficient