problem with petrol indica

sir,
This is krishna from hyd.we have bought an petrol indica 2 years back.we faced a lot and lot of problems with it.now we are been afraid of petrol indica due to its millage and its silencer problems.the freqvent problems that petrol indica gives are as follows
1)silencer problem
2)millage
weather u beleave or not the millage of our indica is 4km per lit
the persons using smoothly are getting 5km per lit
but where as disel indica is very good with millage and all according to millage and all
good millage with disel indicabad millage with petrol indica