Update Feb 2008 - Honestly, Dont do it! I just had a major engine problem due to the gas kit!
I think the only people who have pulled down my review are vested interests who fit gas kits. If you are considering LPG go for a factory fitted one, so you dont end up spending more on maintenance, than what you save.
* Take my advice from bitter experience - it is not worth it!
Update - December 7th 2006
I see that manufacturers have introduced LPG/CNG versions. Remember that 1KG of LPG is 2 litres of LPG. When quoting mileage many magazines conveniently quote 12 km per litre for petrol and 13 kmkg that is actually 6.5 km per litre for LPG. One magazine also quoted the price of LPG as 22 Rs per kg - it is actually close to 28 Rs per litre. So, caveat emptor.
LPG/CNG has almost 20% less energy and the actual cost is same as petrol. It will take a very long time to recover the cost of kit and especially the tank.
A good Diesel car with "Modern" technology should give better economy as Diesel has 30% more energy and is cheaper - but I am not an expert on this.
If gas is sold at 11 rupees per liter it would be attractive. Other cautions given below:
End update Dec 7 2006
====================
I converted my car to LPG for the same reason as others:LPG is cheaper. Believe me, this is the only plus point.I put in an imported gas conversion kit for Rs. 12000 for my MPFI Maruti 800.Fitted at an approved dealer.Pros: as above the only one is saving money.Cons: 1) Rs 12000 is a hefty amount donated by you to the dealer and government(as customs duty or whatever)2)Poor fitting: You know about the quality of Indian goods already. Maruti’s quality is good, but the way the gas kit is fitted is of poor quality, without regard to quality or safety.3) No bill4) No warranty / guarantee(can you expect this from any Indian company?)6) Not only is the fitting bad but so is the concern for other car equipment - in the process of fitting the kit, they disturbed the A/C flow selector.7) You need to periodically drain out some liquid that accumulates(cooking gas odour chemical that is mixed with gas for safety).8) Silly way of holding the cylinder with velcro belts9) No way to know when the gas will finish - yeah, there is a pressure gauge, but I cant make out what the reading is - it is in the boot. And even then cant make out while driving anyway.10) The best part - your car will have much reduced power - you have to drive in a lower gear. If you drive in 3rd gear with petrol, you will mostly drive in 2nd gear in gas. The gears are designed by the car manufacturer for the power and torque developed by petrol not the lower torque and power of gas. You will have an’instant lousy car’ in gas mode.(Of course when you drive in petrol mode you will have an’instant sports car’ feel.)11) Using cooking gas is illegal.12) No standards or government regulations to abide by for the fitters. example - where the gas pipe goes through the body of the car, it is not isolated by a rubber bush, so with constant vibration the pipe will one day have a crack or break.13) Yeah, they will drill(or hammer) a whole(wrong spelling) through the floor of the car to push the copper pipe through.14)What will you do when you smell gas? - there is a seal put by the gas cylinder company which may be not so perfect, but all the same the gas leaks and you dont know how serious it is and one fine day.15) The cylinder will get pretty cold, so to heat it there is a heater pad - it will draw power from the battery.16) God knows what technology gas kit they use - knowing Indian garages, they are selling old tech at new prices and you will not get good economy from the gas - I get only 250 km from one cylinder - confirmed by others I talked to. The dealer told me’at least 300 km and may be 450’, Yeah Right.17) You may damage your engine.18) If you fit an approved gas tank the total kit will cost Rs 23000. Hope you drive a lot to make up that money you spent.19) Filling gas from a petrol bunk is not cheap. 20 Rs per liter is equal to half kg of gas. That is, one kg of gas costs 40 Rs. So you dont save that much money.Well, check it out. Ask for optimistic opinions from others. And those who have better experiences please refute all this. Thanks.xs400