Hi Mr. D. S. Premraj,
This is in regards to your query posted on the website CarDekho.com, we would like to inform you that Nissan Micra is currently not available in automatic transmission. It is available in manual transmission. Nissan Micra petrol gives mileage of 14.0 km/l in city conditions and 18.0 km/l on highways where as Nissan Micra Diesel gives mileage of 18.5 km/l in city conditions and 23.8 km/l on highways. You can use the given link to access the Nissan Micra On-road price.
We encounter similar question many times, the easiest way to increase the mileage is to keep your car healthy. Keep the tyre pressure proper, air filter clean, always follow speed limits and turn off your engine on traffic lights. Find more tricks here- Please find the details Chevrolet service centers here- http://forum.cardekho.com/topic/356-how-to-increase-mileage-of-your-car-tips/
There is not any special petrol recommended for NIssan Micra. You can use simple unleaded petrol in it. However, you can use Speed, Power or Extra premium petrol for better performance of the vehicle.