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Diesel vs Gasoline: Head-to-Head Analysis
The difference between diesel and gasoline is much greater than selecting the appropriate green or black gas pump handle the next time you fuel up. Both fuel types have several advantages and disadvantages that influence the applications in which they excel.
The guide below explores the variances between diesel and gasoline to help you decide which best suits your needs.
What Is Diesel?
Diesel is a dense fuel refined from crude oil in a separate process from gasoline. Many industries — such as automotive, farming, and construction — rely on diesel fuel for power. Public transport bus services, generators, semi-trucks, trains, and heavy-duty machinery also require diesel to function.
Two distinct types of diesel exist: clear and dyed diesel. Refineries produce clear diesel (auto diesel) for on-road use in passenger vehicles, half-ton pickups, semis, and other vehicles that travel the vast road networks throughout the nation.
However, dyed diesel contains a higher sulfur content and can only be used legally in specific applications like aviation, construction, and farming.
Diesel Engines: Compression Ignition
Diesel-powered engines are built specifically to run exclusively on diesel fuel. You cannot put gasoline in a diesel engine and vice versa. Filling up with the wrong fuel — even in small amounts — puts your vehicle’s engine at serious risk.
In a diesel engine, diesel fuel is vaporized and delivered to the combustion chamber. There, it combines with hot, pressurized air and ignites at a higher temperature than a gasoline combustion chamber. The piston’s upward travel compresses the air with each stroke, increasing the air temperature.
Some diesel engines incorporate one glow plug per cylinder, similar to the spark plugs found in gasoline engines. These glow plugs increase the air temperature within the cylinder using a heating element that warms the surrounding air. Higher combustion chamber temperatures make it easier for the diesel fuel to ignite.
Diesel engines also have higher compression ratios, which helps them achieve a higher fuel economy rating. In addition, they lack a throttle body, so the system must introduce more fuel into the combustion chamber to create more power.
On intake, the piston only draws in air in a diesel engine, compared to the air/fuel mixture found in gasoline engines.
What Is Gasoline?
Gasoline is the most prevalent fuel in the United States. It is more refined than diesel and is used in most vehicles on the country’s inner roads. Gasoline is available in several grades, including regular, midgrade, and premium.
Gasoline Engines: Spark Ignition
A gasoline-powered engine requires a spark plug to ignite the air/fuel mixture within the combustion chamber. As the piston compresses, the spark ignites right before the piston reaches the top dead center.
Gasoline engines have a lower compression ratio and control power by introducing more air — and the appropriate corresponding amount of fuel — through a throttle body.
Diesel vs. Gas: Which Is Right for You?
The differences between gasoline and diesel vehicles can be broken down into various features, including cost of ownership, longevity, power, and fuel economy. For drivers and businesses in Indianapolis, understanding the key differences between diesel and gasoline can help in selecting the right fuel type for your needs.
Evaluating which one works best for you requires recognizing where each one excels and how that aligns with your needs. After reviewing the features below, a clear choice should emerge.
Application and Driving Habits
The type of fuel you choose — and the corresponding vehicle powered by that fuel — depends on your intended application and driving habits.
For example, gasoline-powered cars are ideal for everyday driving, such as commuting or running errands, and in most climates. Diesel-powered vehicles can be harder to start in extremely cold temperatures due to their engine design, but they excel at covering long distances.
Cost of Ownership
Diesels tend to cost more to purchase, maintain, and fuel. Recent data shows that regular gas cost $3.082 on February 3 versus $3.660 for diesel on the same day, according to the U.S. Energy Information Administration (EIA). In addition, some diesel services require a specialized mechanic, which can increase maintenance costs.
Many of the parts installed on diesel engines are built to stricter specifications, so they cost more. In the case of fluids, you typically need a higher volume to service the larger diesel engine. However, gasoline cars require more frequent maintenance, albeit often at a lower cost.
Longevity
In the area of longevity, diesels tend to last twice as long as gasoline engines — which have a lifespan of anywhere from 150,000 to 200,000 miles — for several reasons. Gasoline is an acidic fuel that can eat away at engine internals as time goes on. Using high-quality motor oils like Pennzoil can help extend engine life by providing superior protection against wear and deposits. In addition, diesel engine components are often more robustly built to handle the high compression operating conditions.
Granted, the longevity of a vehicle and its engine depends on several additional variables. Regular maintenance and care rank near the top of the list. Driving conditions also significantly affect a vehicle’s service life.
Horsepower and Torque
Gasoline and diesel engines can produce high horsepower and torque ratings. However, among equivalents, diesels tend to make more low-end torque than gasoline engines. Torque at lower RPMs enables diesels to move off the line faster, but in a sprint, gasoline cars often pull ahead, if only for their lighter chassis weight.
Payload and Towing Capacity
Diesel-powered engines excel at long-distance hauls. With higher payload capacity — the maximum weight the diesel vehicle can handle — and a higher towing capacity, diesels are built for the demands of freight.
However, gasoline engines still hold their own regarding payload and towing capacity, especially among half-ton pickups.
Fuel Economy
Gasoline and diesel vehicles tend to get the best gas mileage on the highway. However, gasoline engines fare slightly better in stop-and-go traffic than diesel engines, especially those equipped with stop-start technology. With that said, diesel fuel produces more energy, making it more efficient than the gasoline equivalent.
Indeed, diesels deliver an average of 30% better fuel economy than their gasoline counterparts. Turbocharging a diesel can also significantly increase its efficiency. The turbo supplies the cylinder with compressed air, removing the need for the piston to pull in greater amounts of air on its downstroke.
Emissions
Both gasoline and diesel engines must comply with emissions regulations, although the applicable rules are distinct to each fuel type. For instance, combusted diesel fuel emits more nitrogen oxide and particulates because it contains a greater carbon content than gasoline.
These characteristics require modern diesels to inject diesel exhaust fluid (DEF) into the exhaust to render the nitrogen oxide harmless once it exits the tailpipe.
Top-Quality Fuel Courtesy of the Experts at Cadence
Whether you need gas or diesel in quantity to power your fleet, Cadence’s qualified team members can assist you by delivering value at every turn. Our product and distribution solutions enhance your business and boost your return on investment. Learn more about Cadence fueling services by calling 336-629-2061.
Sources:
Glow Plugs - an overview | ScienceDirect Topics
Advanced Gasoline and Diesel Vehicles | US EPA
Gasoline and Diesel Fuel Update | U.S. Energy Information Administration (EIA)