What happened to the mileage of small petrol cars?

Hi, I am wondering what happened to the mileage of of small petrol cars in India - especially after the release of the Maruti Alto and HYundai Santro (2002) models. I own a Santro LP Zipplus which gives me almost 18kmpl on Delhi city roads. Now I search for small petrol cars and I see cars with a max mileage of 13-14 kmpl. Has the car industry suddenly decided to compromise on fuel efficiency? Style seems to be the selling point these days.

Any insights on this?

Personal insight would be that you were blessed with a very good example of the Santro. Had owned the Santro zipplus for over 6 years and always got 11-12kmpl in the city with 100% AC.

16-18kmpl was possible only on the highways. Most small cars are still efficient, but now i guess (till the advent of the direct injection petrol) its the rule of the diesel cars!

I own a Zen 1998 model. Believe me or not, I get 22 on highways and 15 on city. But 22 on highways is when I drive with a max speed of 65km/hr. I guess we still can get max mileage and its more depending on the style of our driving as well. 

Yeah Sarath,

I believe FE mostly depends on driving style, gear shifting patterns.

I am using my alto lxi since last 6yrs, the mileage has dropped a bit to be frank but still its giving me around 13kpl in city with full A/C.

I feel the kind of maintenance and driving style do have a significant role to play in the FE.

NIk! 

My 55-year-old Fiat Millecento gives me 15 to a litre, so does the Isuzu engine on my Landmaster even though its not the original engine.

The apparent disparity between petrol and diesel seems to be more to do with the excellent efficiency that the current diesel engines provide compared to the petrol counterparts.

The scene for efficient petrol engines will improve leaps and bounds after the introduction of the direct injection petrol engines.

To add… Diesel engines burn less fuel than petrol engines do.  I also understand that fuel efficiency of diesel is not affected as much with the increased load/power as it does in the case of Petrol.

The calorific value of deisel is less than petrol. I.e. it produces less power when burnt, under similar circumstances to that of petrol. It should logically mean that petrol engines should be more efficient. However that is not the case becuase: -

Deisel engines use the direct injection technique (deisel can catch fire more easily than petrol). In this technique the chances of deisel particles going waste (unburnt) are less.

Petrol engines, on the other hand, need an external spark to ignite and continue burning while the piston is pushed backwards. This results in incomplete burning of petrol molecules. Also, not all the power that is genrated while burning could be tapped. As a result, while petrol engines remain more powerful (due to higher calorific value), they are not as efficient.

Benoy is right that when we will have direct injection in petrol engines then their efficiency will increase manyfolds. They should easily surpass the deisel engines in this department. Another big advatage would be a further increase in power output of petrol engines, coupled with cleaner emissions.

All leading players (worldwide) now have these CRDI (Common rail direct injection) version of petrol engines, though they are not yet deployed in mass market cars yet. However, very soon these will become the norm in cars worlwide.