Diesel vs. Gasoline Engines

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Diesel engines and gasoline engines are the two types of internal combustion engines (ICE) widely available on the car market today. These engines differ from each other in one crucial way: how fuel is exhausted in the engine.

In a gas engine, gasoline and air are compressed. At the critical pressure point, the car’s spark plug ignites this mixture, turning it into energy for your car. Diesel engines do not utilize these spark plugs. When air and diesel fuel are squeezed tightly enough, they are able to combust on their own. This is where we get the term compression ignition. All diesel engines function through compression ignition. It is possible for a gas engine to start through compression, but this can incur a great deal of damage. On the other hand, diesel engines are designed for this type of ignition.

So how does this all relate to you? You may not be a mechanic, but you’re wondering how these two engines will affect your driving experience and your bottom line. Here are some things to consider when comparing a gasoline and diesel engine car.

Gas Prices

Diesel fuel costs more at the pump than gasoline, but diesel provides more bang for your buck in terms of energy output. Because of this, most diesel vehicles tend to get 40 or 50 miles per gallon. Overall, the gas cost is likely going to be about the same. Factors like vehicle type and driving style will affect your bottom line, but your gas costs are likely to come out relatively similar whether you’re using a gasoline or diesel engine.

Horsepower and Torque

The power output of gasoline and diesel engines are measured in two different ways: horsepower and torque. Horsepower measures the car’s overall power while torque measures the car’s ability to accelerate and adjust while driving. Because of this, having a lot of horsepower and a small amount of torque will hurt your vehicle’s acceleration. Torque gets heavy loads going, and that’s why we see diesel engines used in big trucks. On the other hand, diesel engines don’t rev up in the way that gasoline engines do. They produce less horsepower than gas engines. For this reason, race cars are built with gas engines to maximize horsepower.

Research over the years has shown that consumers are generally more concerned with torque than horsepower. Most people are looking for fast acceleration and adequate towing ability in a car.


Diesel engines are typically more reliable than gas engines due to their natural build. They rely on compression ignition, the ignition that gasoline engines can’t withstand for long. They are built tough and tend to require little maintenance. Historically, this has caused diesel engines to weigh much more than gas. Due to advancements in manufacturing, this added weight has been reduced quite a bit. Today’s diesel engines still outweigh most gasoline engines, but the difference has shrunk over the last ten years.

Additionally, diesel engines are more simple in design due to not having spark plugs or the attached electrical wiring. Generally speaking, diesel engines can travel many more miles and run for several hundred more hours before they require their first major service.

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