LPG characteristics vs petrol characteristics
Petrol :
- Fuel consumption in petrol engine is less when compared to LPG.
 - Petrol has odour.
 - Octane rating of petrol of 81.
 - Petrol engine is not as smooth as LPG engine.
 - In order to increase octane number petrol required lead additives.
 - Carburetor supplies the mixture of petrol and air in the proper ratio to the engine cylinders for combustion.
 
LPG :
- Fuel consumption in LPG engine is 10 % increase as compared with the petrol.
 - LPG is odourless.
 - Octane rating of LPG is 110.
 - Due to higher octane rating, combustion of LPG is smoother and knocking is eliminated and the engine runs smoothly.
 - LPG is lead-free with high octane number.
 - The vaporizer function as the carburetor when the engine runs on LPG. It is a control device that reduces LPG pressure, vaporizes it and supplies to the engine with a regular flow of gas as per the engine requirement.
 
If you use petrol or LPG as a fuel in car then they differ by following category :
- LPG costs about 40% less than petrol and diesel, in part because of a lower fuel duty.
 - LPG is a cleaner burning fuel compared to the above two, but releases even lesser heat than petrol.
 - Engine life can be improved due to LPG being a cleaner burning fuel.
 - Maintenance is more in LPG used car as compared with petrol.
 - LPG vehicle owners pay less road tax than petrol vehicle.