you guys r posting ideal mileages 
i hope im not dreaming, zubair530 says his cultus does 215km in one tank full. how is it possible? never had anything better than 130kilo meters and now you says your cultus do 170 kilometers. raaz kia hay bhai???
depends on the way u drive n on the routes u drive.. drive on constant & steady rpms.. rather than pushing the accelerator to its limits.. always be aware of the tyre pressure, tyres low on air can result in poor consumption. driving on higher gears gives u better mileage than switching between the first 3 gears again n again.. zubair use to travel on motorways so 215 is what he gets whereas i have never gone beyond 171... and keep in mind that 171 was when i was to be the only one in the car with no other passenger (daily from office to home n vice versa).. each n every kg weight in your car affects consumption. imagine that your car according to factory specs weighs somewhere around 900 kg.. the G10 engine alone weigh around 63kg 
... now when ur car gets old it carries too much mud n dirt underneath so it adds up a few more kgs.. consider your own weight, suppose 70kgs.... and when there are lets say 4 passengers in your car it means ur car is carrying around 280kgs load on it!!! add your 50kg CNG cylinder and around 6-7 kg gas in it!!!! all this ends up your 993cc engine carry more than 1500kg of weight so one could expect it to perform it this way.
there is no defined pattern to calculate the average of a car's consumption. it depends upon so many things, each of which affects the consumption drastically. the quality of fuel, filters, tyres, their pressure, load, driving style, driving routes, tuning etc etc.. if all goes well together then you will get best mileage.. 171 which i acheived isn't an average mileage, the next time i refilled, i got 140! the reason being the routes, the passengers and the change of filling station as well... so if i calculate, the average turns out to be somewhere between 145-160 km... otherwise 130km as u mention isn't a bad mileage for an in-city driving, be happy
