Which is more powerful or efficient-petrol or diesel engines?
Petrol engines are widely considered to be the most efficient of engines, because they are more refined than diesel. Since diesel is not completely refined, it cannot completely combust and so does not (in theory) produce as much energy per litre of fuel as a petrol engine. However, some diesel engines can be made to be much more efficient than petrol engines because they have a different type of fuel, and burn it in a different way.
