Diesel Fuel vs. Unleaded Gasoline


Automotive Editor

Armaan Almeida no longer works for CarsDirect. He was an Automotive Editor who produced buying guides and sneak previews, in addition to publishing daily news stories and tracking monthly deals, incentives and pricing trends from Toyota, Nissan and Lexus.


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, Automotive Editor - February 19, 2015

When it comes to diesel fuel compared to gasoline fuel, both options have their pros and cons. Gasoline reigns supreme in the United States, but diesel is more popular in Europe. If the emission standards in the United States were a little lower, diesel cars may be more popular since they would be more readily available. Both fuels do have their benefits, but both also have their disadvantages. Here is a comparison between the two fuels.

Diesel MPG Cost Comparison Guide vs. Regular Gasoline Engines

When it comes to diesel MPG ratings, they can help you save some money on your fuel costs. Diesel fuel is typically used in larger trucks, but there are a rising number of cars that run on diesel fuel. Diesel fuel is more popular in Europe than the United States since Europe has less strict emissions standards that allow them to have diesel vehicles, whereas in the United States, not all diesel cars are allowed.

Diesel Advantages
Many people choose diesel over gasoline for its distinct advantages. Diesel does get more fuel economy than gasoline, and not by a slim margin. Diesel is more than 33% more efficient than gasoline is when it comes to your fuel mileage. This means if you were to get for example, 30 miles to the gallon, a diesel equivalent engine would get 40 miles per gallon. Diesel needs to be run through a diesel engine, and diesel engines offer more torque than a gasoline engine. Torque allows for great acceleration, which also accounts for the great fuel economy numbers.

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Diesel Disadvantages
Diesel engines are typically louder than gasoline engines, although technologies have been developed that have helped to limit this as much as possible. Diesel is also a dirty fuel and causes dirty emissions. Diesel fuel does cost more than gasoline, although it is usually within around 20 cents of the price of regular gasoline. This may be thought of as disadvantage, but can it truly be considered a disadvantage? Let's delve into the prices and fuel economy to see if the cost of diesel is worth it.

Concerns Relating to Fuel Usage

In a straight comparison between diesel and gasoline engines, there are a number of things which can be considered. Using gasoline in cars is a mainly American tradition, as there have always been a high percentage of diesel cars in Europe. If you're looking for a good reason not to purchase a car which runs on gasoline in the future, there are a number of cases in which diesel is much better, and more efficient.

  • Environmental concerns. This is the primary reason why many people choose to use a diesel car, and in this debate it certainly has benefits in both using less fuel per mile, and also making less CO2, or carbon dioxide. But the diesel fuel is not completely pollution free, and in fact has been shown to produce carcinogens, soot and NOx, which can be just as harmful to the environment. It is a good idea, then, for designers to create filters and catalytic converters for diesel engines which help to reduce even this risk of pollution, making environmental concerns a good reason to purchase diesel.
  • Financial considerations. There is very little difference between the two fuels in this heat. Diesel may be cheaper than gas half the time, but for the other half it is more expensive, so they are both about the same when it comes to the price of the fuel itself. However, diesel autos get better gas mileage, so there is a saving in that direction. Gasoline cars are cheaper as new purchases, as diesel cars can be around $700 more expensive.
  • Engine performance. Surprisingly, the diesel fuel and engine combination can produce better engine performance, although this is lessened when the diesel use is bio-diesel, or other forms of enhanced fuel such as black diesel. If you intend to use the latter, then you will probably find that gasoline engines will outperform diesel cars.
  • Noise and smoothness of ride. This is another area where the gasoline car can easily out-do the diesel. While the latter no longer produces smoke under the bonnet, or horrible roaring noises, it is still louder than the gas car. You will also experience less of a smooth ride from your engine, which can make the drive a less pleasurable experience.

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Diesel vs. Gasoline
Diesel is becoming an increasingly popular fuel source for vehicles in the United States, and there are many benefits to using this kind of fuel, not the least of which are improvements in the performance of your engine, and a reduced pollution problem. The benefits of gasoline include a smoother movement through the engine, meaning less noise and restricted movement, and the cheaper cost of cars which run on gasoline, although it is only a matter of time before cheaper diesel cars are produced.

Diesel Fuel Economy (MPG)

One of the reasons that people are buying diesel vehicles is for the diesel fuel economy. For many years, people have been driving around in diesel powered cars and light trucks for the convenience of having something that they don't have to fill up as often. However, when you want to compare specific diesel MPG ratings you will see some startling information as to just how good diesel fuel economy is.

Look Deeper than Just Engine Sizes
One of the mistakes that people make when they want to compare regular gas to diesel powered engines is that they only look at the size of the engine. This will show you how much gas a particular engine will need, but not how well the overall vehicle will perform compared to gas mileage. You must look at the rest of the factors involved.

Fuel Economy Differs between Car Types
Fuel economy is a funny thing. Depending on the type of vehicle you're driving, you will find different numbers. Smaller hatchbacks and sedans will deliver greater diesel fuel economy than will larger trucks and SUVs. However, when compared as a whole, you will see that the savings in both fuel and in money are much improved that just a few years ago.

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Head to Head Comparison
Looking at the same sized engine, in the same size vehicle, you will be able to make a better comparison of the two types of engines, and see the real results of diesel performance. If you take into account that diesel and gas prices were the same thing, you would, over the course of a year, save approximately $2,000 in fuel costs with a diesel powered engine. There are many factors that are the reason for this, but the savings are shown in the actual results.

More Efficient
When you burn diesel fuel, there is a different dynamic happening within the engine. While there are many similarities with both engines, the main difference is the actual combustion process. This is where the economic value is. Diesel is not mixed with the air the same way that gas is. In a diesel engine the air is brought in at the top of the cylinder and then compressed greatly to where the air heats up to an igniting point. The diesel is then injected as a small mist. The super heated air ignites and the piston is pushed by the explosion. This is a much more efficient manner and does not waste as much gas by mixing the two at the beginning.

Savings at Purchase
The savings are not only found in the diesel fuel economy. When you buy the same vehicle--but with different engines, you will see a savings in price. A 6.0L diesel powered engine will cost you less than an 8.0L gas powered engine. Both have the same performance rating, but the diesel is going to give you a better price.

Towing Economy
Diesel engines have long been used in larger vehicles because of the power of the engine and the lower cost of gas. Since diesel has escalated in price, the savings are still there, as the newer engines actually use less. It is not unusual to see more than 30 MPG on a light duty truck or SUV.

Buying a Diesel Auto: 8 Diesel Fuel Facts to Consider

Automobiles that run on diesel fuel provide customers with positive fuel economy. At the same time, a diesel engine that saves its owner money through gas expenses has the ability to cost the owner through repairs and maintenance. Like any auto, those that use diesel fuel require a learning curve. Whether or not the consumer believes the proven advantages outweigh the disadvantages will always remain a matter of personal choice. Knowing the facts regarding diesel fuel will give customers a better base to determine their choice.

High MPG Rating
Diesel fuel provides customers with an alternative that lasts longer than gasoline on a per gallon basis. Owners enjoy this benefit while driving all sorts of diesel powered auto choices, including both trucks and cars.

Comparable Cost to Gas per Gallon
Many consumers have come to understand that diesel fuels no longer fall below gasoline costs. Generally, diesel fuel will cost the same on a per gallon basis when compared to gasoline. This price comparison always differs depending on the stage and time of the economic cycle. In some cases, diesel will actually cost more than some grades of gasoline.

Engine Maintenance Differences
A large number of consumers choose diesel powered autos due to their positive fuel economy ratings. Unfortunately, this factor leads the same group to look past the differences in engine maintenance when compared to gasoline engines. The engines found in gasoline powered cars have large differences when compared to diesel powered counterparts.

Diesel fuel powers engines with different features and working capabilities. A diesel powered engine has no spark plug connections or engine distributors. This ensures customers that certain engine tune-ups will never need to take place.

Slow Burning Power Source
One main factor that leads to the high fuel economy provided by diesel fuel lies within its physical and chemical properties. Diesel fuel has a higher boiling point than both gasoline and water. It takes a longer amount of time to evaporate diesel fuel because of its heavy, oily nature.

Availability of Diesel Fuel
Not every gas station offers its consumers with diesel fuel pumps. Many diesel owners find fuel sources in commercial truck stops along expressways. Customers must consider the availability of diesel fuel when considering a diesel car or truck purchase.

Diesel Fuel Engine Noise
Diesel fuel powers engines that produce more noise when compared to gasoline cars. The difference stems from the mechanical composition of the engine types and the fuel getting burned through differentiating processes.

Diesel Pollution Levels
The burning of diesel fuel causes more visible pollution than gasoline. Burning diesel does in fact produce less carbon emissions when compared to gas, though. These two facts serve as trade-offs to one another, providing customers with a choice regarding their effect on pollution.

Lessened Sport Performance
Cars that run on diesel tend to provide their customers with less agility and speedy responsiveness. Instead, diesel fuel increases an automobile's towing ability and endurance. These factors produce yet another tradeoff for potential customers.

A Diesel Gas Mileage Comparison: 6 Highest Rated Vehicles

When it comes to diesel gas mileage, it blows gasoline engines out of the water. Diesel mileage comparison to that of gasoline is often not even close. Diesel engines get at least 30% to 35% better fuel economy numbers than gasoline engines do. Diesel engine cars are more often found in Europe than the United States because diesel has more emissions (of certain combustion byproducts) when compared to gasoline. Only 42 out of 50 states even allow diesel vehicles due to their emission standards. Many people are starting to choose diesel engines though because it costs nearly the same as gasoline, but it is much more economical. Not to mention, diesel engines are also much quieter than those from years ago, which was a big downside to diesel vehicles. Here are some of the top rated diesel vehicles.

  • The best diesel truck mileage would probably be the Chevy Silverado Hybrid. It has a heavy duty Duramax diesel engine, and can produce 22 miles per gallon on the highway, and 21 miles per gallon in the city. Diesel pickup mileage is typically much lower than this since their trucks are often heavy and powerful, but the Silverado is a diesel hybrid that allows it to be fuel efficient.
  • The best diesel mileage is obtained by the Jetta TDI. The Jetta TDI comes as a sedan, as well as a wagon. It gets 40 miles per gallon on the highway, and 31 miles per gallon in the city, for a combined rating of 35 miles per gallon. It is cheap, and offers great fuel economy.
  • The Golf is also comparable to the TDI. It is more expensive, but offers the same economy numbers. It gets 42 miles per gallon on the highway, and 30 miles per gallon in the city. It is about 25% more efficient than the Golf gasoline engine version.
  • The BMW 335d is also on the list, but it is far below the Jetta's mileage mentioned. The 335d gets 36 miles per gallon on the highway, and 23 miles per gallon in the city, for a combined rating of 29 miles per gallon. It is also much more.
  • The Mercedes E320 Bluetec is another option, and is more expensive than the Jetta and BMW options. It may provide the most luxury, but definitely not the best economy on the list. It can get 32 miles per gallon on the highway, while still getting 23 miles per gallon in the city. Not the best, but still highly respectable, it does carry the high price tag though.
  • If you are looking for a diesel SUV, you may not have the best selections to choose from. The Jeep Grand Cherokee CRD would be your best option. The Jeep can get 25 miles per gallon on the highway, and 20 miles per gallon in the city, for a combined rating of 22 miles per gallon

Diesel Fuel Saver Scams and Schemes to Avoid for Better Gas Mileage (MPG)

Just like get rich quick schemes, any product that claims dramatic instant boost in fuel economy is most likely not a diesel fuel saver. Although there are products that can help improve your vehicle's efficiency, it can be tough separating the legitimate ones from the scams. This article will help you decide what is best for you.

Believe it or not your right foot has the greatest impact on your fuel economy. You will see the greatest improvements in miles per gallon (mpg) by simply changing you driving habits. The best part is it won't cost you a dime to see dramatic gains. The first step is to slow down and drive at the posted speed limit. Unlike gasoline engines, diesel engines efficiency is greatly affected by the engines revolutions per minute (rpm). For example a gasoline car driving at 75 mph may only lose 1 to 1.5 mpg versus driving at 65 mph. A diesel can lose as much as 5 mpg by driving 75 mph versus 65 mph.

Aside from changing your driving habits, there are some steps you can take to improve the efficiency of your vehicle. Replacing the stock air filter with an aftermarket one such as a K&N filter will allow your car to breathe better. A new air filter will address oxygen flow on the intake side, and a less restrictive exhaust system will help the car breathe on the outtake side. Both of these modifications improve the flow of oxygen through your engine, which determines how efficiently your engine burns fuel.

For older diesel vehicle or vehicle with higher mileage, carbon build up on valves can impact the engines efficiency. Carbon on the valves reduces the flow of oxygen in to the cylinders, hurting fuel economy. Using an engine cleaning additive can help to reduce the carbon build up, allowing the engine to operate normally again.

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, Automotive Editor

Armaan Almeida no longer works for CarsDirect. He was an Automotive Editor who produced buying guides and sneak previews, in addition to publishing daily news stories and tracking monthly deals, incentives and pricing trends from Toyota, Nissan and Lexus.


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