Although cost of petrol is more than that of diesel the price petrol car is lower than that of diesel car.the pollution create by diesel engine is more than that of petrol engine.diesel can create more knocking in engine than that of petrol.Hence petrol car has more life than that of diesel car.less fumes are produce from petrol engine in compare to that of diesel engine .so to minimise environmental pollution , more life span petrol engines are more suitable than that of diesel engines.