Seeing as that a large part of the population reside in rural parts, the cause for mini car boom becomes evident. One other factor is that these cars can easily seat 5 persons, thus accommodating a full family. These cars, also naturally have lesser operational costs compared to the big cars, thus making it more popular. Mileage offered by the small cars is one factor definitely in its support.
Cost of maintaining a small car or the cost for its service is definitely much less. With this we can conclude that this is definitely the key reason why they are a hit in India.