Hello all; I have been thinking about this for some time and searching through the internet for it but couldn't get a satisfactory answer for it, so i decided to ask this to you. Here is my question: If diesel fuel has more energy in it than gasoline does and if diesel engines are more efficient than gasoline engines, why do diesel engines create less power? For example, a car with a 1.4 diesel engine cannot exceed 130 km/h on a straight road but a car with gasoline engine with the same properties (except it's a gasoline engine:) ) can go up to 150 km/h. As far as i know, obstacles to speed on a straight road is just the air friction and that means gasoline engines produce more power (P=F.V), don't they? Im stuck here and I will appreciate any help from you, thank you for your interest.