Here at TGMO, we are often asked, “What’s the difference between Gas & Diesel Engines?” So, we decided to write a blog post about the main differences as well as the pros and cons of each. So let’s get right into it!

How It Works — Gas vs. Diesel Engines

The two most popular types of engines in cars today are gasoline engines and diesel engines. Gas engines run on gasoline. Diesel engines, on the other hand, run on a type of oil called diesel fuel.

What’s the Difference Between Diesel and Gas Cars?

The major difference between gas and diesel engines is that gas combustion happens outside the engine, while diesel combustion happens inside the engine. This is because gas needs to be pressurized to ignite and burn in an engine, while diesel does not need this extra boost for ignition.

 How to Tell the Difference Between a Gas and Diesel Car Engine

Gasoline engines are typically cheaper to buy, more fuel-efficient in urban areas and have a higher power-to-weight ratio. Diesel engines are more robust, have a longer lifespan but are less fuel-efficient off highways. Diesel engines can use many types of fuels, while gasoline engines only use gasoline.

Diesel Engines:

They are internal combustion engines in which ignition is caused by the high temperature of the air in the cylinder due to mechanical compression.

Only air or air with remaining combustion gases from the exhaust is inducted into the chamber during the intake stroke and compressed during the compression stroke.

Gasoline Engines:

Are also internal combustion engines in which ignition is caused by coils creating a spark. The fuel and air are often mixed before compression. Some modern engines use direct cylinder injection too.

Modern cars come with electric gasoline pumps installed inside the fuel tank. While a carburetor is used in some older engines, and fuel is supplied by a mechanical pump instead.

The Pros & Cons of Gasoline and Diesel Engines

Diesel Engines:

✅ More mileage — One of the main selling points for diesel engines is their fuel efficiency. Diesel engines can save 25-30% more fuel than gas ones.

✅ More power — Diesel engines can handle higher weights because they have more torque and a better power-to-weight ratio.

✅ Fewer emissions — Modern diesel engines emit way less CO2 and carbon monoxide.

❌ High fuel costs — The cost of diesel fuel has been a barrier to the widespread acceptance of diesel cars.

❌ High price tag — A car with a diesel engine is typically more expensive to buy than its gas counterpart.

❌ Noisier — Modern diesel engines are less noisy than years past, but they are still louder than gas engines.

Gas Engines:

✅ More mid-range power — Gas engines have a lot of torque in the mid-range and at high rpm.

✅ Greater capacity — Capable of running at high engine speeds.

✅ Fewer repairs—- As gas engines are more widely used, they can benefit from lower service and repair costs.

❌ Limited lifespan — A gas engine will turn twice as many RPMs on the highway as a diesel engine.

❌ Lower thermal efficiency — A diesel engine is around 20% more thermally efficient than a gasoline engine.

❌ Fuel volatility — Fuel volatility impacts engine start, warm-up time, fuel distribution, and engine performance.

 

Now that you know the key differences between gas & diesel engines, which type is right for you? Let us know in the comments below.