Gas vs. Diesel: What’s the Real Difference?


Ask your average American about a diesel, and they’ll likely say something about big trucks or black smoke. Ask the average European, and they’ll wonder why Americans don’t put diesels in all of their cars. So who has the right idea?

Both, as it turns out! Geographical preferences boil down to the price of fuel, and both engine types have important advantages and disadvantages.


Engines make their power from igniting fuel. Gas and diesel engines differ in how they ignite it.

Gasoline engines use compression and spark plugs. In your engine, gas and air swirl together to create a flammable mixture. The engine’s pistons compress that mixture, which is then ignited by a short burst of electricity from a spark plug.

Diesel engines skip the plug. Instead, they compress that air-fuel mixture so highly that it explodes without spark. These huge forces mean diesel engines are built stronger and last longer…but at a higher cost.


The fastest cars in the world use gasoline engines, and the biggest trucks use diesel engines. They’re powerful, but in different ways. It comes down to a question of horsepower vs. torque.

Torque is low-end, get up and go power, the force that squeals tires and slams you against the seat. Diesels produce way more torque than gas engines, making them ideal for low-speed hauling. Torque usually drops off as an engine moves faster, making it hard to maintain at high speeds.

If torque is what gets a car going, horsepower is what keeps it going. It gradually increases as an engine moves faster, which is why racecars produce low torque and extreme horsepower. This predictability is also more user-friendly than torque. Gas engines produce more horsepower than diesels.


Though gas technology is improving, diesel engines are nearly always more efficient. For instance, the diesel VW Golf gets 7 more mpg on the highway than the gas version. Gas engines also rely on complex computers for their spark component, something that diesels don’t need.

However, diesel engines do create more noise, noise that a muffler alone can’t remove. Their clacking sound is unmistakable, and may bother some people.

Does your gas or diesel-powered car or truck need maintenance? Fast Lube Plus can perform the oil change, diagnostic, or spark plug service you need. Contact us today!