Why is Diesel More Economical than Petrol

Diesel has been a primary fuel used for heavy vehicles across the GCC. The superior mileage, higher power output and compression ratio give a tactical advantage over petrol when it comes to transportation across long distances. Fuel suppliers in Dubai who cater to large organisations offer diesel fuel mainly. Although the penetration in the private segment is dominated by petrol-based engines, we will be discussing why is diesel more economical than petrol.

Difference between diesel and petrol engines
Fuel Efficiency
Since diesel-powered engines are more cost-efficient on highway roads than petrol engines, consumers who drive long distances on highways often prefer diesel engines. A large role in fuel efficiency in engine combustion factor is played by the Compression ratio. Diesel engines are usually 25 - 35 % more fuel-efficient than petrol engines of comparable size. Unless driving in city traffic, the overall diesel engines costs per kilometre are lesser than petrol engines.

Energy and Torque
Diesel fuel packs more energy per litre than petrol fuel. Diesel cars also tend to have more torque, which results in more impressive acceleration. Besides, to get a fair comparison between diesel and petrol power, we have to compare an 8-litre petrol engine with a 6-litre diesel engine

Fuel price
The fuel price of diesel and petrol in the UAE are almost similar with diesel being slightly cheaper. Combined with the better fuel efficiency and lower prices, getting more economy from a diesel engine over the life of the vehicle is easier. Fuel trading companies in the UAE have helped in maintaining the price.

Durability
Diesel engines are naturally more durable and last longer than petrol engines giving minimal required maintenance and reliable operation provided timely and professional maintenance is done. Thanks to modern manufacturing methods, diesel cars do not weigh relatively more than comparably sized petrol vehicles

Also compared to petrol engines, diesel engines have fewer components meaning fewer potential parts that could malfunction. Most diesel engines require fewer maintenance services as well as repairs resulting in an overall economic saving.

Volatility
Diesel has a low self-ignition temperature and hence is a non-volatile fuel. Diesel engines used compressed ignition whereas petrol is highly volatile and requires a spark plug to ignite. This factor makes diesel fuel last much longer and easier to store. Many fuel trading companies in  UAE find this trait advantageous.

Noise and Air Pollution 
This is one area where petrol-powered cars take the lead. Diesel engines are notoriously famous for being noisy and emitting nitrogen oxides and sulfur oxides which are harmful to the environment. Worn out diesel vehicles emit dark soot, especially when accelerating from a dead stop. With technological advancements, these issues have been mitigated to a level but still haven’t caught up with the driving experience and relatively lower pollution contribution from a petrol engine. 

Why do diesel engines consume less fuel?
Unlike electric vehicles, diesel and petrol engines use internal combustion to generate power.  Air containing oxygen enters the engine and combines with fuel in this type of engine. The resulting mixture is compressed by the engine's cylinders which ignites to trigger the movement of the piston and crankshaft. The crankshaft activates the transmission of the vehicle to turn its wheels. The piston then returns back to its starting position and expels the spent gas from the engine as exhaust through the tailpipe. This process repeats several times per second to drive the vehicle. Comparatively, diesel engines have better compression ratios. The compression ratio is defined as the difference in the volume of a cylinder between the moment the piston is at the bottom of a cycle(the cylinder has the most volume)  and the moment the fuel combusts as the piston is moving up.

The ignition process, however, differs for petrol and diesel engines. During the compression process, ignition is achieved with the help of a spark plug in a petrol engine. Spark plugs are not available in diesel engines and simply use extreme compression to generate the heat required for spontaneous ignition. This is also called compression ignition. Petrol engines are not built to withstand compression ignition. 

Due to the lower compression ratio, the maximum value of thermal efficiency achieved is almost 20% lower in a spark-ignition engine compared to that of combustion ignition engines. Hence diesel engines need to supply relatively lesser fuel to achieve the efficiency required. 

Another point to note is that engines with more cylinders tend to offer more power and smoother operation. However, more power means less efficiency and more complications to fix.  

Pros of buying a diesel car

• Fuel Efficiency: Better mileage means fewer trips to the fuel pump stations.
• Car Maintenance Cost: Fewer parts compared to petrol cars. Also no need for ignition tuneups
• Engine Power: Increased torque, faster initial acceleration and better-towing capabilities. 
• Pollution and Emissions: Less carbon is emitted into the atmosphere since it’s more fuel-efficient. Also, there is biodiesel which is produced from Renewable Resources but it does lead to decreased engine performance.
• Overall Costs: Longer-lasting engine, Lower fuel cost and higher resale value. 

Now you can understand why diesel is more economical than petrol. Overall, diesel is a good alternative to petrol as a fuel source and is gaining popularity in fuel suppliers in Dubai and mid-sized vehicles for personal uses as well in the UAE.