Advantages and Disadvantages of Diesel Engines

Pros / Advantages Of Diesel Engine :

Greater efficiency. Up to 40% less fuel consumption than similiarly performing gasoline engine. This is because of their much bigger compression ratios and due to diesel fuel having greater energy content than gasoline.
Greater torque at low RPM’s. This is very useful when towing heavy load or going uphill, makes accelerating easier. This is because of their longer strokes, which extert more leverage on crankshaft.
More than double longetivity. Diesel engines generaly cover more than 600,000 km(400,000 miles) without rebuild. Of course oil and filter changes are mandatory. This is because diesel engines are made with stronger components to withstand high compression ratios and temperatures. There are recorder diesel engines covering more than 1 milion km(750,000 miles) without rebuild
They have no high voltage electrical ignition system, resulting in high reliability and easy adaptation to damp environments.
Although diesel fuel will burn in open air using a wick, it does not release a large amount of flammable vapor which could lead to an explosion.
Diesel engines can accept super- or turbo-charging pressure without any natural limit, constrained only by the strength of engine components. This is unlike gasoline engines, which inevitably suffer detonation at higher pressure.
Emits around 27 times less carbon monoxide than gasoline engines.

Cons / Disadvantages Of Diesel Engine :

Average diesel engine has poorer power to weight ratio than similiar displacement gasoline engine. This is because diesel engine must operate at lower RPM’s due to heavier components and heavy rotary parts, however, modern diesel engines actually are on par or have greater power than similiar displacement gasoline engines because they accept turbo-charging without limit. For example BMW 320d it has 180 HP and around 50–60 MPG(4–6 L/100 km) compare that to Smart Fortwo. It has tiny 70 horsepower and consuming more fuel.
Average new diesel car will cost around 5–15% more than same car with gasoline engines
Are more noisy. I am pretty sure you are familiar with characeristic diesel clatter. This is because of its combustion cycle introducing high pressure fuel into higly compressed air and sudden combustion.
Average cost for repairs cost more than repairs for gasoline engine.
Despite lower CO2 emissions, diesel engines emit more sulphur, NX1 and particles which affect human health. Some particles are even known to cause cancer.
Difficulty starting in cold weather. This is because of lacking spark ignition, relying only on heat of compressed air for combustion. Below -15, it can be very difficult to start a diesel engines. However, some modern diesel engines are equipped with engine heaters which migitate this problem to some extent.