Planning to buy a new car?

Based on public reviews and brand popularity you might have already decided on the car brand you prefer, but have you considered whether you need a gas engine car or a diesel engine?

Which gives more mileage? Which one is more economic and fuel-efficient?

We bet you haven’t put much thought into this aspect while car shopping, but don’t worry by the time you finish reading, you will be an engine expert.

Three gasoline pumps with different colors and octane rating stickers captioned “Gasoline Vs. Diesel: Which Car to Buy?”

Gas vs. Diesel: Scientific Difference

Traditionally gas and diesel are both produced from mineral oils, but their refining methods vary. When compared to gas, diesel is easier to refine but it contains more pollutants that need to be extracted and the per liter energy content is roughly 15% more than gas.

Diesel fuel is denser and contains 39.6 MegaJoules/Liter of energy compared to 33.7 MegaJoules/Liter of gas.

Now let’s take a look at other aspects t hat differentiate the two.

How does the car engine work?

Both the diesel and gas engines are internal combustion engines, which mean that the fuel and air are mixed inside the engine and then the mixture is compressed internally in the cylinders.

Due to this compression, the fuel ignites pushing the piston inside, rotating the crankshaft. This rotation ultimately turns the wheels connected to the vehicle’s transmission. The piston then moves outside and pushes the burnt gases out from the exhaust.

The cycle repeats itself several times per second. The number of cylinders an engine has, the more smoothly it runs and generates more power.

Gasoline vs. Diesel Mileage

A diesel engine does not require a spark plug and hence has a higher compression rate than a gas engine.

A diesel engine is bigger and difficult to construct which adds to the price of the car. But the fact that the diesel engine provides better mileage makes it easy to cover the additional cost paid initially.

Since diesel contains more energy (39.6 MJ/L), so less fuel is required to produce the same amount of force as gas.

Output Power

The power output of an engine is measured in terms of torque and horsepower. While horsepower is a direct measure of the power generated, torque defines the rotatory force of the engine on the driveline.

In order to get the vehicle moving, torque comes into play and that is why big trucks that move heavy loads employ diesel engines, but diesel engines generate less horsepower as compared the gasoline engines hence sports cars mainly use gas engines.

Diesel vs. Gas Engine Reliability 

Diesel engines employ compression technology. They are built tough and sturdy, but they are also a little bulky.

However, modern manufacturing techniques have greatly reduced the bulkiness and the engine weight is quite manageable.

Since a diesel engine does not require a spark plug and the associated electrical system, it is simpler compared to gasoline engines and with added mileage and reliability it delivers the same performance.

In comparison, a diesel engine can outlast a gas engine when it comes to several miles or hours before requiring a tune up hence saving on repair bills and proving to be more economical. 


Pollution has been one of the major reasons why diesel cars have had such a hard time gaining popularity among the masses. The burning of diesel fuel produces more pollutants than burning the same quantity gas does.

Incidences like Dieselgate have worsened the situation. Diesel engines are known to produce more nitrogen oxide which can be linked to serious health hazards and smog. It also produces a lot of soot, black stuff produced by burning of sulfur, which is a part of diesel fuel.

So, all in all, there is no clear winner. The choice, however, needs to be made on the usage and keeping in view the above-mentioned factors.

If you are looking for a car for normal usage and like to buy another car every other year, then choose a gas engine car. However, for heavy usage such as hauling your boat or trailer and if you plan to use the car for a long time a diesel engine car is probably your best bet.

Not all gas stations carry diesel fuel but if you buy a diesel type engine you can use certain websites and download an app that can be excellent digital tools for you to find a gas station for you.