About Diesel SUVs

Concerns about the poor gas mileage of sports utility vehicles has caused many in the automobile manufacturing industry to look for ways of improving the automobiles' image. Diesel SUVs offer many benefits to the consumer and are relatively inexpensive to produce. The result is a profusion of diesel-powered SUVs from almost every manufacturer.

Significance

Diesel is a type of fuel that can be derived from many sources, though the most common is petroleum (oil). As a liquified hydrocarbon fuel, diesel is different from its petrochemical cousin, gasoline, in several ways. First, the fuel is more viscous than gasoline; this density makes it less flammable when stored, and thus more than an equivalent amount of gasoline. Second, diesel fuel is not ignited by a high-voltage spark, but instead relies on a constantly-hot ignition source, called a "glow plug," and extreme compression to cause ignition. This means that a diesel engine can continue running even if a battery is dead or almost dead. Finally, unlike gasoline, diesel fuel offers a more complete burn, reducing greenhouse gas emissions. In a consumer vehicle such as an SUV, these differences translate into more power at a higher fuel efficiency than a similarly-sized gasoline powered vehicle. Diesel engines used to be associated with a "knocking" sound and unhealthy-looking black smoke emissions. Current fuel technology, however, has corrected many of those problems, making newer diesel SUVs legal in all 50 states.

Types

SUVs have suffered from poor gas mileage in recent years as efficiency was sacrificed for power. With a surge in gasoline prices from 2007 to 2008, more prospective buyers shied away from purchasing SUVs, which hurt the bottom lines of many auto manufacturers. In response, alternative engine configurations such as diesel were experimented with. Currently every major manufacturer of SUVs has a popular model type with a diesel engine option. Ford, GM, BMW, Mercedes-Benz and Jeep are five of the major nameplates with the largest concentration of diesel SUVs available for consumer purchase.

Time Frame

In the late 1970s and early 1980s, diesel powered cars, most notably German imports, were marketed as an alternative to higher efficiency, gasoline-powered Japanese cars. These diesels were largely panned because for their loud engine noise and unappealing, sooty exhaust. Because of federal regulation, as well as state emissions guidelines, diesel engines had been relegated to delivery and service vehicles for decades. Since at least since 2005, however, more SUVs have been made available in diesel powered models. The change is partly due to revised federal fuel emissions and economy specifications as well as advances in diesel fuel refining. Currently, diesel fuel made from petroleum is called "Ultra-Low Sulfur Diesel" or ULSD. The elimination of the majority of sulfur in diesel makes it a much more clean burning fuel than its predecessors. Additionally, some other technological breakthroughs have decreased emissions even further, often meeting or exceeding EPA requirements.

Considerations

In fall of 2008, Mercedes-Benz began selling "urea injected" diesel SUVs. The "urea" injection, also called "urea NOx (or urea Nitorgen Oxide)," causes a more powerful, hotter combustion and reduces less particulate matter (soot) significantly. The "urea tank" is added about every 15,000 miles during routine maintenance. BMW's 335d and X5 are diesel-powered German SUVs. The BMW model also uses urea injection and a filtration system similar to Mercedes-Benz's. Jeep's Grand Cherokee and Loredo, both of which debuted in 2006, are using what Jeep terms "Bluetec" technology which is a version of the urea system in the German SUVs. Older diesel vehicles, such as the General Motors Suburban, Jimmy and Blazer, have been available in diesel models since the early 1980s, but the new Denali and Yukon promise to offer a more efficient and cleaner ride than their predecessors. Ford offered diesel engines in its now-defunct Excursion model until 2005, but continues to offer a similar engine in the Explorer and all its subsets, making the most popular line of SUVs competitive with other nameplates that offer more variety.

Expert Insight

Currently in the United States, diesel fuel is taxed at a higher rate than gasoline. This is because of its prevalent use in shipping commerce (trucks, trains, and ships, for example), but also in recognition that older diesel technology and refinement techniques produced a fuel which caused far more pollution than gasoline did. There is some speculation, however, that so-called "bio-diesel," diesel derived from plant material such as peanut oil or corn oil, may alter this taxation structure to make the fuel more attractive to consumers. Biodiesel is also said to be a more clean burning fuel than "petro-diesel," diesel made from petroleum, as well as promoting greater energy independence.

Resources

• Mercedes-Benz "urea injected" diesel SUV
• Carguide's list of diesel SUVs, cars
• Biodiesel.org's overview ove bio-diesel