Why Is Diesel More Expensive Than Unleaded?

On a dollar-per-gallon basis, on-highway diesel fuel costs have been higher than regular-grade gasoline prices virtually continually since September 2004. This tendency contrasts with the prior historical pattern of diesel fuel prices being lower than gasoline prices, with the exception of harsh winters when demand for heating oil drove diesel fuel prices higher. Diesel fuel costs have been higher than conventional gasoline prices in recent years for three key reasons:

  • Diesel and other distillate fuel oils have seen strong demand, particularly in Europe, China, India, and the United States.
  • In the United States, the move to less polluting, lower-sulfur diesel fuels had an impact on diesel fuel production and distribution costs.
  • On-highway diesel fuel has a federal excise tax of 24.3 cents per gallon, which is 6 cents per gallon greater than gasoline.

This Week In Petroleum delves into the world of petroleum markets. This FAQ topic is covered in greater depth in the May 20, 2009 and March 26, 2008 editions.

Other FAQs about Diesel

  • Does the EIA provide state-by-state estimates or projections for energy output, consumption, and prices?
  • In the United States, how much biomass-based diesel fuel is produced, imported, exported, and consumed?
  • How much carbon dioxide is created by gasoline and diesel fuel consumption in the United States?
  • How much does a gallon of gasoline and a gallon of diesel fuel cost?

Why is diesel more expensive than gasoline?

The cost of diesel fuel is higher. Diesel fuel is subject to a higher federal excise tax than gasoline (24.4 cents per gallon vs. 18.4 cents per gallon for gasoline), and diesel fuel is occasionally subject to a higher state tax.

Why is unleaded cheaper than diesel?

Customers who drive a lot of highway miles prefer diesel engines, according to Bell Performance and Road and Track, because they are more efficient on these roads than gas engines. Diesel fuel simply has more energy per gallon than gasoline, making it more cost-effective overall. Diesel engines are still more fuel efficient than gasoline engines, but they are less so for city drivers. Diesel cars also have higher torque, which means they get better gas mileage and accelerate faster.

It’s crucial to keep in mind that some types of diesel fuel can reduce vehicle performance. Black diesel, biodiesel, and other improved diesel products are among them.

Diesel and gasoline are around the same price for most Americans. Diesel can sometimes be more expensive than gasoline, yet it can also be less expensive than gasoline. Even if you pay more on diesel fuel, a diesel engine will still provide better fuel efficiency throughout the life of the car. This is because an 8-liter gasoline engine would be required to produce the same level of power as a 6-liter diesel engine.

Diesel engines, according to Digital Trends, are more durable and endure longer than gas engines, with reliable operation and low maintenance requirements. Diesel cars used to be substantially heavier than comparable-sized gas cars, but thanks to contemporary manufacturing technologies, this is no longer an issue.

Diesel engines also have fewer components than gasoline engines, reducing the number of potential parts that could fail in your vehicle.

Diesel engines often require fewer repair and maintenance services than gasoline engines, resulting in a cost savings.

While early diesel engines had a well-deserved reputation for being noisy, current technology has largely addressed this issue. Noise pollution and dark smoke have been reduced, so if you were concerned about those issues in prior decades, you may wish to reconsider diesel as a viable option. Today, the driving experience in a diesel-powered vehicle is essentially identical to that of a gasoline-powered vehicle.

Why do diesel engines last so long?

A gas engine would have reached the end of its life 20 years ago at about 100,000 miles, but today’s engines are constantly making another trip around the odometer. However, while gasoline engines can now reach 200,000 miles and beyond, diesel engines can also reach 500,000 miles and beyond. The following are three reasons why diesel engines survive longer than gasoline engines:


We’ve all learned the hard way that larger isn’t necessarily better. Diesel engines, on the other hand, are designed to endure longer than their gasoline equivalents. Compression ratios and cylinder pressures are higher in diesel engines than in gasoline engines. Diesel engines are designed with these factors in mind. Their crankshaft and camshaft are larger, necessitating larger bearings and stronger main and rod bolts. Increased clearance from larger crankshafts and camshafts provides for greater oil flow. Better engine lubrication means reduced engine wear, which extends the engine’s life.

Other significant design features of the diesel engine contribute to its durability, including:

  • Most diesel engines feature a gear-driven construction, which means you won’t have to worry about timing belt issues. This also saves money on costly maintenance because the timing belt does not need to be replaced.
  • Piston cooling jet – Piston cooling jets spray engine oil on the bottom of your pistons in diesel engines. This engine oil spray protects pistons from premature wear by keeping them properly lubricated, which lowers friction and keeps them cool.
  • There are no spark plugs in diesel engines, so the gasoline burns more slowly. Because of the slower burn, there is less stress and more torque, which is essential for diesel engine efficiency.

Diesel Fuel

The fuel that diesel engines burn is another reason they survive longer than gasoline engines. Diesel fuel is a form of distillate fuel made primarily from crude oil, which allows diesel engines to wear their cylinders out more slowly than gasoline engines. This adds diesel fuel lubricating qualities, extending the engine’s total lifespan. On the contrary, gasoline is mostly composed of aromatic hydrocarbons, which function similarly to harsh and corrosive solvents. This lack of lubricity causes your engine’s components to wear out prematurely. Diesel engines have lower exhaust gas temperatures (EGTs), which contributes to their increased lifetime. Despite the fact that diesel fuel has 139,000 British thermal units (BTUs) compared to 115,000 BTUs for gasoline, the principles of thermodynamics dictate that the higher compression ratio diesel engine’s expansion rate actually cools the exhaust gases faster. The first flame front is cooler due to the lower auto-ignition temperature of roughly 410°F for diesel fuel compared to 495°F for gasoline. Diesel engines also have a substantially lower air-to-fuel ratio, ranging from 25:1 to 70:1, compared to 12:1 to 16:1 for gasoline engines. EGTs are cooled by a lower air-to-fuel ratio. In addition, gasoline burns more faster than diesel fuel. Because of the slower laminar speed of the flame during combustion in diesel engines, there is less shock to the rotating assembly, which adds to their durability.

Lower RPMs

The third factor that determines how long a diesel engine lasts is its operating efficiency. In comparison to a gas engine, diesel engines have lower revolutions per minute (RPMs) and produce more torque. The ability to create the same power at lower revolutions implies less wear on your pistons, rings, cylinder walls, bearings, valves, and guides, extending the life of your engine. When diesel engines are not in use for long periods of time, they are usually left running. The regular cycling of turning the engine on and off saves wear compared to a gasoline engine since a major percentage of wear occurs at starting. It also decreases heat cycles and maintains stable operational temperatures.

Expert Spotlight:

PSP Diesel in South Houston, TX, is known for their 6.0L Ford Powerstroke builds, and Stephen Peters has this to say about why diesel engines survive longer:

“Diesel users often use their engines for far more than what they were designed for. In contrast to the conventional start/stop patterns of a gasoline engine, this is typically done to generate maximum torque and run for longer periods of time during the day. They aren’t exposed to abrupt starts and stops. One of the most abrasive actions on a motor is starting it. While idling your engine is not good for its longevity, that is exactly what the majority of these trucks are doing. They run long hours and are worked very hard because they are started at the beginning of the day and shut off at the end, but that is their job.”

Peters continues, “Diesel engines are simply intended to be more durable. For example, the blocks are larger, the walls are thicker, and the pistons are larger. And, even with the extra weight, let alone the tight tolerances in the rings to avoid blow-by, the design was created with lubrication in mind, reducing friction and damage to the rubbing parts.”

Is diesel easier to make than gasoline?

Diesel fuel is less volatile and heavier than gasoline, making it easier to refine from crude oil. As a result, diesel is generally less expensive than gasoline in most countries.

Why is diesel cheaper in California?

While crude oil prices are falling across the country, diesel costs in California continue to be significantly higher than the national average. In California, increased diesel prices are due to a number of factors. The following are some of the reasons:

Higher fuel taxes in California contribute to the state’s high relative diesel costs. Californians, in fact, pay more fuel taxes than inhabitants of 46 other states. While California’s gas tax is 68 cents per gallon, Nevada’s is 33 cents and Arizona’s is only 19 cents.

California, unlike the majority of other states, imposes percentage-based taxes in addition to per-gallon taxes.

Furthermore, fuel prices have risen significantly in recent years as a result of the California state government’s Cap-and-Trade policy, which has resulted in an increase in fuel production costs. Fuel taxes are collected in California to fund maintenance, transportation, and construction initiatives.

Californians must use fuel that has been specifically blended to meet the state’s environmental guidelines. Special winter and summer blends are available, which help to enhance air quality. However, there are only a few refineries that make these mixtures. Fuel prices rise by roughly 5-15 cents per gallon due to the limited availability.

Gasoline prices in California are mostly determined by the type of fuel used. Dyed diesel is typically less expensive than clean diesel. As a consumer, the wide range of fuel costs in California can seem perplexing at first. It is crucial to note, however, that dyed diesel is recommended for off-road applications, whilst clear diesel is primarily used in automobiles on the road. As a result, while clear diesel is subject to a variety of taxes, colored diesel is exempt from the majority of them.

When compared to other states like Arizona, California has a substantially higher average land value. As a result of the high cost of leasing land in California, the cost of operating a gas station is also high. Furthermore, in California, complying with smog management and groundwater pollution standards is costly. As a result, the expenditures of operating and maintaining a gas station are considerable. When you add in a high minimum wage compared to other states, it’s no surprise that California’s fuel is more expensive.

In addition to these causes, there are a slew of refinery troubles in California that are driving up diesel prices. You may reduce the impact of these difficulties on your fuel costs by searching around for the best fuel prices and purchasing from a reputable source.

When did diesel become more expensive?

The average price of diesel is $3.17. Since September 2004, on-highway diesel fuel costs have been consistently higher than ordinary gasoline prices.

Which is cheaper diesel or gasoline?

The most obvious benefit of choosing diesel is that it is far less expensive to fill up than a gasoline engine. You’ll also save money on gas, especially if you do a lot of highway driving and long travels. Diesel engines are also designed for heavy-duty use, thus major engine overhauls are uncommon over the vehicle’s lifetime. In diesel mills, torque statistics and towing capacity are significantly more important.

Is diesel worse for the environment?

When diesel fuel (refined from crude oil) is used, it emits a variety of hazardous emissions, and diesel-fueled vehicles are major emitters of pollutants like ground-level ozone and particulate matter. The US Environmental Protection Agency (EPA) created limits for the sulfur content of diesel fuel and emissions from new diesel engines to address this issue.

What mileage is too high for a diesel car?

Of course, there are exceptions to every rule, but these vehicles aren’t worth the risk. If you absolutely must have a high-mileage vehicle, go for the petrol model with the largest engine.

A smaller engine will be pushed to 90% of its capacity under the same driving conditions, whereas a larger engine will cruise at 70%. Less stress equals fewer repairs.

“Is automobile age or miles more important?” I’m regularly questioned when it comes to older vehicles. When compared to a newer car, an older car always wins – which makes obvious when you think about it…