Diesels are Dirty
Myth! The modern diesel engine is a clean and efficient machine. While diesels were not held to equivalent standards as gasoline engines for many years, today's diesels utilize technology that reduces NOx and particulate emissions. And by the nature of their higher efficiency, diesel engines produce comparatively lower amounts of CO2. Exhaust gas recirculation (EGR) systems and selective catalytic reduction (SCR) technology minimize NOx emissions. Diesel particulate filters eliminate up to 99% of particulate emissions (the black soot diesels often produce), and diesel oxidation catalysts (DOC) scrub carbon monoxide emissions.
Diesel Powered Vehicles are Only Good for Towing
Myth! Diesel engines are versatile and well suited for many applications. The diesel cycle is very efficient and the fuel packs a higher energy content, making comparable diesels more economical than gas engines. In fact, diesels were originally introduced into the light duty pickup market for the purpose of providing an economical alternative to gas engines. General Motor's 6.2L diesel was never intended to be a workhorse when it was adapted to their 1/2 ton pickup platform, but it was good for 25+ mpg when driven conservatively.
Diesel is also the fuel of choice for towing needs because it offers a considerably flatter torque curve and produces more torque at lower engine speeds. They can also provide superior fuel economy in small commuter cars. The 2010 Volkswagen Jetta TDI, for example, is rated at an EPA estimated 30 mpg city and 42 mpg highway. Diesels are used extensively in Europe and other countries, where drivers are more familiar with their benefits.
Diesel Engines are Slow and Sluggish
Myth! The diesels of the 80s and even early 90s certainly were not designed to win any races, but modern diesel cars and trucks have power-to-weight ratios comparable to their gas burning counterparts. Not only are diesel engines coming from the factory with comparatively high horsepower and torque ratings, there is no shortage of aftermarket support for more common engines.
Diesel Engines get Poor Fuel Economy
Myth! As previously discussed, diesels typically achieve better or comparable fuel economy to gas engines. The fuel content of diesel fuel is on the order of 10% higher, diesels can operate at leaner air-to-fuel ratios, and higher compression and turbocharging improve efficiency significantly.
Diesel Engines Have a Higher Cost of Ownership
Myth! All things considered, owning a diesel can be cost effective. While service costs are marginally higher, service intervals are often longer and less repairs will be required during the engine's life. Additionally, diesel engines can be expected to operate much longer before a major overhaul is required. Diesels are more robust, meaning the engine's life expectancy is much greater than a comparable gas engine. Million mile gassers just don't exist, but Ford, GM, and Chrysler have all offered diesels that have been known to rack up hundreds of thousands of miles without the need for major repairs.
Diesel Engines are Noisy
Myth! Diesel engines have a distinct knock to them, but modern diesels are quiet enough that you can have a conversation over the hood. Automakers have made considerable strides in reducing NVH (noise, vibration, harshness) and today's engines sound nothing like they did a decade ago.
Diesel Fuel is Hard to Find
Myth! Diesel fuel is available at most fuel stations. Since there are fuel stations at nearly every city block around the country, finding diesel fuel is not a difficult task. For those in rural areas, finding diesel shouldn't be a problem, as the demand for diesel is typically high.
Diesels are Difficult to Start in Cold Weather
Myth! Diesel engines rely on compression ignition rather than spark plugs, but glow plugs and/or heater grids in the intake track give diesels the heat necessary to start. Additionally, block heaters are included with most engines sold in colder climates, which make starting a diesel in sub-zero temperatures a breeze.