Well, these cars are said to be based on the not-so-popular Reva(launched sometime in the 90s), as seen below. Reva was not popular cuz it was a battery powered car which ran a max of 80km on a full charge. But the concept of an ultra small car was popular, so the companies put 2 and 2 together and out came Nano and Yeni.
In highly populated countries, these cars would be very appreciated. Here is the Reva btw
