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Buying Diesel? Some Pros and Cons to Consider

Mar. 07, 2024

When you are shopping for a new car, you have many options. Some cars are available with diesel engines, and you may be wondering whether buying diesel is a good idea. 

Until recently, most of the diesel-powered vehicles in the United States were trucks because diesel motors are much better suited for large, heavy vehicles such as tractor-trailers, construction vehicles, and school buses due to considerations like durability and the cost of owning a diesel truck vs. a gas-powered truck. 

However, passenger cars with diesel motors are gaining in popularity, and carmakers are producing more of them each year. If you are asking yourself, “Should I buy a diesel car?” you may find it beneficial to weigh out the pros and cons associated with these types of vehicles. 

Just make sure that no matter which type of vehicle you choose to buy, you're covered by a good car insurance policy. Local independent insurance agents can help you find affordable coverage.

What Is a Diesel Engine?

Most people know how to tell if a truck is diesel, since many on the road are not very well maintained and typically have an offensive odor and emit smoke when starting up or accelerating. This may deter you from wanting a diesel car. However, a well-cared-for diesel car will not have these problems and is often indistinguishable from traditional gas-powered vehicles.

Before we start looking into diesel engine pros and cons, let's talk about how a diesel engine is different from a traditional gasoline-powered engine. 

Both types of vehicles have combustion engines, but they differ in how they ignite the fuel to power the vehicle. Gas-powered cars use spark plugs, whereas diesel engines use extreme compression, which generates enough heat to ignite the fuel. 

If you put gasoline into a diesel engine, the generated heat would not be sufficient to ignite the fuel and the car would not run. If you put diesel fuel into a gas-powered car, you would destroy the engine as soon as you turned it on. Fortunately, diesel fuel pumps are designed to not fit into gas-powered cars to deter people from making this error.

The following are several pros and cons when considering diesel vs gas cars.

Fuel Efficiency and the Diesel Engine

The main reason that many people choose to buy a diesel car is for the improved fuel efficiency the cars can offer. So, does diesel get better gas mileage?

CarsDirect reports that a diesel car will frequently get about 30% to 35% more miles per gallon than the same car with a gasoline-powered engine. If you own a truck or SUV, the difference in gas mileage is usually lower but still about 20% higher than a gasoline-powered truck or SUV.

It is worth noting, however, that diesel fuel is more expensive than gasoline. If you are used to using only premium gasoline, this cost difference will be less apparent to you. But for those who like to fill up with the least expensive option, paying slightly more than the cost of premium fuel may be hard to swallow at first. 

Fortunately, because of the increased gas mileage, your trips to the pump will be less frequent. Even with the increased cost of diesel, you can expect to pay less in fuel costs each year.

Another thing to keep in mind is that traditionally, not all gas stations have offered diesel fuel. The good news is that with the rise in popularity of diesel vehicles, nearly two-thirds of gas stations in the US, including all newly built gas stations, currently offer diesel as a fueling option.

Finally, the area in which diesel engines excel most is in highway miles. If the bulk of your driving involves frequent stopping and starting for traffic lights, traffic, and stop signs, your mileage difference will be far less apparent and you may be better off with an electric car or a hybrid. However, if you spend a lot of time on the highways, you stand to save a lot of money in fuel costs.

In summary:

  • Pros: Better fuel efficiency, fewer trips to the pump
  • Cons: Higher cost to fill up, not all gas stations carry diesel

Car Maintenance Considerations

You may be wondering, are diesels expensive to maintain? They may be, but it usually balances out in the end.

In some ways, diesel-fueled engines require less maintenance. This is because these vehicles do not use spark plugs or distributors. Thus, there will be no need to have ignition tune-ups done. 

However, keeping your engine well-maintained with regular and frequent oil changes, along with air, oil, and fuel filter changes, is absolutely necessary. Diesel cars are also be equipped with water-separator collection bins that you must empty manually.

Failure to keep your diesel engine maintained with routine care can result in dire consequences. The fuel injection system can break down and require expensive repairs. Additionally, you may need to have a dealership or certified diesel mechanic do repair work, and these professionals work at a much higher rate.

In summary:

  • Pros: Fewer parts, no need for ignition tune-ups
  • Cons: Regular maintenance necessary, increased costs for repairs

Engine Power: Diesel vs. Gasoline Engines

Why is diesel better when it comes to towing and transporting heavy loads? The answer is the reason that so many trucks have diesel engines: the high amount of low-end torque they can produce. This is one of the top considerations of people who ask, "Should I buy a diesel or gas truck?"

A diesel-fueled car, truck, or SUV can accelerate more rapidly from a complete stop than a gasoline-powered car, and these vehicles have far better towing capabilities. 

Another one of the benefits of diesel engines is that they are powerful and long-lasting. If you are purchasing a truck or SUV that you will frequently use to tow or haul very heavy items, then a diesel-powered engine may be the best choice for you.

However, with the increased torque comes decreased horsepower. This means that diesel-fueled cars are not very zippy. If you are the type of person who enjoys speed, you may be disappointed with your car’s performance if you buy a diesel car. But if you are looking for a strong and steady engine that will get the job done, buying diesel may be the best choice for you.

In summary:

  • Pros: Increased torque, better towing capabilities, faster initial acceleration
  • Cons: Decreased horsepower, less speed

What about Noise and the Smoothness of the Ride?

Traditionally, diesel-powered engines have had the reputation of being stinky, noisy and clattery. This gave these vehicles a bad reputation and is one of the main reasons that they didn’t get a strong foothold in the American marketplace until recently.

Today’s diesel cars benefit from current technology and building methods that make for a much quieter and smoother ride. 

However, despite these improvements, diesel owners might notice that their cars' engines are not as smooth or quiet as their gasoline-powered counterparts, and they may make an occasional clacking or clattering sound. The question is whether the increased noise comes at a level that you find acceptable.

In summary:

  • Pros: Vastly improved noise level and smoothness of diesel engines
  • Cons: Not as smooth and quiet as gasoline-powered engines

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Pollution and Emissions: What You Need To Know

Another reason that diesel cars didn’t take off in America as they did in Europe is their dirty emissions. Emission standards in the United States are much stricter. Anyone who has ever had the misfortune of driving directly behind a school bus or construction vehicle is aware of the smell and dark soot that these vehicles often produce, particularly when accelerating from a dead stop.

Fortunately, today’s diesel cars run much more cleanly than they did just a few years ago, and they are able to meet the emission requirements laid down by the government. Those who are concerned about the environment will like the fact that they will be using less of the non-renewable fuel source that vehicles require. Some people may even consider using biodiesel, which is an option, though it does lead to decreased engine performance.

On the downside, however, despite the cleaner emissions that catalytic converters can provide, diesel cars still pollute the air, particularly when accelerating from a complete stop. Some of the particulates in the emissions of these cars include carcinogens, soot and nitrous oxide. If you will be doing frequent city driving or you want to own a vehicle that is good for the environment, you may be better off with a hybrid or electric car.

In summary:

  • Pros: More fuel efficient, less carbon emitted into the atmosphere, run much more cleanly than earlier diesel engines
  • Cons: Diesel emissions release carcinogens, nitrous oxide and soot into the air

Overall Costs: Saving Money in the Long Run

When considering the cost of owning a diesel car, the first thing you may notice is that these cars are more expensive to purchase. 

Why can diesel cars and trucks get so expensive? It has a lot to do with the weight of the engine block. Although diesel vehicles generally cost more to purchase than their gasoline counterparts, you can recoup most of this cost at the gas pump if you keep your vehicle for long enough.

One of greatest advantages of a diesel engine is that it is very long-lasting, which makes your car’s trade-in and resale value much better. In fact, Deanna Sclar, author of Auto Repair for Dummies, 2nd Edition, reports that there are several Mercedes-Benz diesel-fueled vehicles that have exceeded 900,000 miles on the original engine.

If you plan to keep your car a long time and to provide it with frequent routine maintenance, you can expect your vehicle to save you money in the long run. If, however, you are lax on the upkeep because of the increased cost of having a diesel mechanic work on it, buying a diesel car may end up balancing out or costing you more in the long run.

In summary:

  • Pros: Lower fuel cost, higher resale value, longer-lasting engine
  • Cons: Diesel vehicles are more expensive, diesel mechanics are more expensive

What Are Some of the Best Diesel Vehicles Available Today?

It is difficult to compare the gas mileage offered by diesel-powered and gasoline-powered cars because EPA estimates tend to be generous for gasoline-powered cars but very conservative for the diesels. That said, however, these are the mileage estimates for some of the most popular diesel-powered cars on the market today, along with their gasoline-powered counterparts.

These are some of the most recommended diesels, as reported by Edmunds, CarsDirect, Consumer Reports and AutoTrader:

  • Volkswagen Jetta TDI: A top choice of Consumer Reports, the Jetta averages 35 mpg and has a low cost-to-own ratio.
  • Volkswagen Golf TDI: This car has a sporty suspension, a convenient hatchback, and a well-equipped interior. It can achieve mileage as high as 42 mpg on the highway.
  • Volkswagen Passat TDI: This car is similar to the Golf but has more interior space. In testing, Edmunds found that it frequently exceeds 40 mpg gallon on the highway.
  • Jeep Grand Cherokee EcoDiesel: AutoTrader likes this American-built SUV with a towing capacity of 7,400 pounds. They report that it can “achieve 30 mpg highway, giving it best-in-class efficiency.”
  • BMW X5 xDrive35d: A top choice of both Edmunds and AutoTrader, this SUV gets much better torque and fuel economy than the gasoline-powered version, and its sharp handling makes it fun to drive.

Of course, many other diesel vehicles provide exceptional quality and gas mileage, so be sure to read reviews of any that you may be interested in.

Do You Think a Diesel Is Right for You?

Only you can decide whether a diesel car is right for you. These cars have the potential to save you a lot of money. 

An independent agent may not be able to advise you on which type of car is best for you, but these agents can certainly help you find an affordable car insurance policy that matches your coverage and budgetary needs once you've found the perfect vehicle. Find an independent insurance agent near you to learn more.

Diesel engines have been around since the late 1800s, and in the decades since they’ve grown from a novelty in the world of power generation into the driving force of industries the world over. We’re taking a look at some of the pluses and minuses of these revolutionary machines to help you decide if a diesel engine is right for you. 

Some of diesel engines’ biggest drawbacks have been substantially improved in recent years, such as their penchant for polluting, loud noise, and difficulty starting in cold weather. However, there are still a couple of issues to consider before jumping on-board the diesel train, just so you know what to expect. 

 

Pro: Powerful

Diesel engines are the workhorses of the power industry. They’re installed in the heavy-duty trucks, container ships, and trains, used for towing the biggest loads and meeting the most demanding prime power generation needs. 

Although diesels aren’t known for horsepower, their chief ability is in the torque they can provide, which is much more than a similarly sized gasoline engine can muster. Torque is what gives them the “oomph” needed to get up to speed and get work done at low power, making them great at towing and accelerating quickly out of the gate. 

 

Pro: Efficient

Diesel engines are inherently more efficient than gasoline engines because of their combustion method and lower fuel consumption. Unlike gas or petrol engines, which use a spark plug to ignite the air-fuel mixture in the combustion chamber, the diesel engine compresses the air inside until it’s hot enough to spontaneously ignite the fuel when it is sprayed into the chamber. (Speaking of which, no spark plugs or distributors also means no ignition tune-ups for diesels.)   

When it comes to fuel, diesel contains up to 15% more energy than gasoline, allowing diesel cars to travel up to 35% farther on a gallon of fuel, according to the U.S. Department of Energy. 

To learn more about why diesel engines are so efficient, check out our article on the subject. 

 

Pro: Reliable

This is one of the primary reasons so many backup generator owners opt for diesel-powered units: diesel engines are about as dependable as it gets. Because they have to be able to withstand the higher compression during operation, diesel engines are typically built to be more rugged, which can lend them longer lifetimes than other engines.

However, it’s important to note that diesel engines are no different than gas or other types of engines when it comes to the need for routine maintenance. A well-cared-for modern gasoline engine may last as long as a diesel engine. It’s also true that tighter environmental regulations for diesel engines have altered the long-standing fact that diesel engines are simpler machines with fewer moving parts–the new technology that’s required to achieve these standards can wear out, no matter what type of engine it’s in. 

To read more about the lifespan of a particular type of diesel engine, see our article on how long diesel generators last. 

 

Pro: Good Resale Value

Diesel engines’ performance have earned them a great reputation, one that is reflected when it comes time to remarket one. Consumers in the market for pre-owned engines are looking for ones that have a lot of life left in them and won’t be a big fixer-upper project to get them in working order. A diesel that’s seen regular maintenance checks all these boxes and commands a premium price.

 

Con: Prone to Wet Stacking

Hindered performance and even permanent damage are the negative consequences of a diesel engine that falls victim to wet stacking. 

This problem, applicable only to engines that run on diesel, results from operating the engine for long periods of time below the necessary operating temperature, with an incorrect air-to-fuel ratio, or too much or too little fuel. Any one of these scenarios can cause unburned fuel to gather in the exhaust system in the form of black ooze. 

Nevertheless, responsible owners who follow best practices as laid out in their manual will never experience this potential disadvantage of diesel engines. 

 

Con: Fuel is More Expensive

Diesel fuel was historically lower-priced than gasoline, but that has changed since around the turn of the millenium. Several factors have contributed to this, including popular demand for diesel, higher production costs due to stricter environmental standards, and a higher federal excise tax on diesel than on gasoline. 

In addition, in 2014 the Environmental Protection Agency established standards that require minimum refill levels of an additive called diesel exhaust fuel (DEF) for both road and non-road diesel engines. DEF helps reduce the amount of nitrous oxide from entering the atmosphere by converting it to separate molecules of nitrogen and oxygen. Although it’s better for the environment and improves performance, DEF is still an added cost for diesel owners to contend with. 

Still, because diesel engines are so efficient, their fuel costs per kW of power produced is still typically lower than that of other engines, making this “con” often a moot point. 

Buying Diesel? Some Pros and Cons to Consider

Pros & Cons of Diesel Engines

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