Question

why diesel is used in heavy vehicles?

Answer 1

We know diesel is more compressive than petrol, so we use diesel engines because size of the diesel engine is small compared to the petrol engine ,for heavy vehicles.

Answer 2

Because Diesel, as a fuel, has slower combustion characteristics as compared to petrol. So, for a given power, they produce higher torque at low speeds, which is the primary requirement of a heavy engine.