Why mechanical efficiency of diesel engine is greater than petrol engine?

The mechanical efficiency of diesel engines is generally greater than that of petrol engines due to several factors. Diesel engines operate at higher compression ratiOS, which leads to better thermal efficiency and more complete combustion of fuel. Additionally, diesel fuel has a higher energy density and lower volatility compared to petrol, allowing for more efficient energy conversion. Furthermore, the inherent design of diesel engines, which often features simpler components and less throttling during operation, contributes to their overall mechanical efficiency.