herkul

What about petrol which remain in fuel pipe to the engine? And what about air which came in pipes?

I believe you should buy a car you like. You will have it a few years, so don't calculate cost difference if it is not very big. Sometimes you should buy something for your better life. Especially when you are buying secondhand car you can't predicts all costs neither with diesel or petrol engine. And both are expensive when you have to fix it.