Difference between Diesel and Petrol Vehicles/Engines


Most of us usually wonder what is the difference between a petrol and a diesel car and whyon earth do we usually have both kinds of engines running on road vehicles.
Other than the smoothness noticed in a petrol engine , the basic facts that differentiates a petrol and a diesel car are as follows

->Petrol Engines fire with the help of a spark plug (produces a spark to ignite petrol) while Diesel engines do not need a spark plug to ignite. Diesel engines have a self ignition property. As the air compresses inside, the diesel which is injected gets burnt due to the high compression and temperature. So the next time you see a spark plug ad from MICO, remember that these are only used for petrol engines.

->Petrol Engines are less fuel efficient than Diesel Engines as a matter of fact. Although we find that a Maruti 800 has a very high fuel efficiency of around 17-20kmpl,in reality Diesel produces more energy per given unit of fuel .This means Diesel engines are more efficient than petrol Engines for a given power rating. That’s one reason why Diesel is the most common fuel used for higher rated engines, such as trucks and buses. Diesel‘s thermal efficiency makes it better suited for heavier vehicles than petrol.

-> Another important point of difference between the Diesel and petrol Engines is their reaction to the accelerator pedal. While modern petrol engines usually inject fuel proportional to the accelerator pedal. That means, the more you accelerate, the throttle directly releases more percentage of petrol and air to burn for the power. While in Modern Diesel engine, the accelerator pedal and other pressure conditions are also taken into picture to release the diesel for burning. This is one main reason why we see that petrol cars virtually listen to your accelerator demand , while Diesel cars (without a turbo) do have a slight lag. However, with the improved Common rail diesel Engine and turbo chargers, Diesel cars are almost neck to neck with the petrol cars.

-> Diesel cars have a higher torque (turning power) when compared to petrol cars. So when you are driving uphill on a lower gear, you might be surprised that a Diesel car will take lesser effort to drive up because of the Diesel’s higher thermal efficiency and higher generation of torque. That’s another reason why heavy vehicles tend towards Diesel engines because they need higher torque to even get the vehicle moving.

While it is a personal choice to buy a petrol or a diesel car, one needs to remember that Diesel engines are also built to last longer.

click here to decide whether to buy a diesel or a petrol car