Posted Saturday, May 22, 2021
Over the past 40 years, most automakers offered diesel engines in the U.S. at some point. Now, though, diesels are much rarer, found mostly in pickup trucks and a handful of cars and SUVs.
Diesels have never been as popular in the U.S. as they have been overseas, where high gasoline prices and tax incentives make them more economical choices. In the U.S., historically low gas prices have stunted demand for more fuel-efficient engines, and in recent years, hybrid gas-electric and electric-only powertrains have pushed diesels further aside.
In addition, after Volkswagen was caught cheating on diesel emissions tests a few years back, that virtually killed demand for diesel-powered cars and SUVs in the U.S. Volkswagen, as well as Audi, Mercedes-Benz, BMW, and other brands, pulled most of them from the U.S. market.
Diesel engines, though, still have a loyal following, particularly among those who tow heavy boats and trailers, which explains why they remain popular in pickup trucks.
Fiat Chrysler Automobiles offers diesels in its Ram pickup line and the Jeep Wrangler, and Ford and General Motors in their pickup trucks. Jaguar Land Rover is the only other manufacturer offering diesels in the U.S. for the 2020 model year.
Here are the key pros and cons of diesel engines compared to gas engines:
Pros of Diesel Engines
Higher Fuel Economy
Diesel engines are 20% to 35% more efficient than conventional gasoline engines, so they wring more energy from the fuel and deliver more mpg. For example, the 3.0-liter turbocharged diesel V6 engine in the Chevrolet Silverado is rated at 25 combined mpg by the EPA, compared to 19 mpg for the gas 5.3-liter V8. In the Ford F-150, a 3.0-liter turbodiesel gets 24 mpg, six more than for a turbocharged gas 3.5-liter V6. Heavy-duty pickups, such as the Silverado 2500 and 3500, Ford F-250 and F-350, and Ram 2500 and 3500, are not rated for fuel economy by the EPA, but owners say that the diesel versions get better fuel economy than their gas-driven brethren.
Diesel engines typically last longer than gas engines, especially under grueling towing conditions, because diesels are typically built with stronger parts designed to stand up to sustained hard use. For this reason, diesel engines are often the preferred choice of fleet operators, such as delivery services and utilities. Those companies want to keep vehicles in service as long as they can – 300,000 miles or more – to reduce costs, and diesels are often regarded as a better long-term bet than gas engines.
Cleaner Diesel Vehicles Are Available
Modern diesel engines produce fewer pollutants thanks to better emissions systems and diesel fuel that has lower sulfur content. Companies that make diesel vehicles and diesel fuel capitalized on those advances by touting their products as “clean diesel.” Diesel engines in cars and light trucks must meet the same emissions requirements as gas engines. Some scientific studies have shown that current diesels are as clean or cleaner than gas engines, except for the amount of nitrogen oxides they produce. Nitrogen oxides, or NOx, cause smog.
Cons of Diesel Engines
Higher Initial Cost
Diesels are more expensive than gas engines, sometimes by knee-buckling amounts. On the Ford F-150, for example, a version with the 3.0-liter turbodiesel engine costs $4,000 more than one with the standard gas V6 and $3,000 more than one with a 5.0-liter gas V8. On the heavy-duty Ram 2500, a 6.7-liter turbocharged Cummins diesel engine adds $9,300 to the bottom line.
Higher Maintenance Costs
Diesel engines usually have larger oil capacities than gas engines and may require more-expensive types of oil. For example, a Ford 6.2-liter gas V8 engine takes 7 quarts of oil, but their 6.7-liter diesel takes 13 quarts. So that $29.99 oil change you see advertised probably won’t apply. As an example, one Ford dealer in Florida was advertising a $59.99 price for The Works (an oil change, tire rotation, and basic service package) for gas cars and $129.99 for F-Series pickups with a diesel V8. When something breaks on a diesel engine, it’s likely to cost more to replace than on a gas engine because diesels use heavier-duty parts and have more elaborate and specialized emissions controls to reduce particulate emissions. In addition, not every mechanic has the tools or training to work on diesels, so there may be fewer options for who can do the work.
Diesel Fuel Can be More Expensive and Harder to Find
Diesel fuel is easy to find along interstate highways, but not every station in the suburbs or in a downtown metro area will have it, because diesel requires a separate underground tank and a separate pump. Refueling with diesel at some stations can require that you fuel up next to 18-wheelers or other large trucks. In addition, when someone spills gasoline on the pavement at a station, most of it evaporates. Diesel fuel, however, is an oil, so it leaves a puddle or a greasy stain.
Not as Useful in Sporty Cars
There’s a reason you don’t see diesel engines in many sports cars – diesel motors can’t match the performance of gas motors when you want a lightweight, high-revving, high-horsepower engine. Because diesel engines have heavier blocks, lower RPM redlines, and favor torque for towing over horsepower for high-speed acceleration, they’re better in trucks than performance cars.