In a previous blog, we discussed hybrid vehicles and their pros and cons. Diesel is another alternative fuel that may give you improved fuel economy, plus more diesel vehicles are making their way into the marketplace.

Modern diesel engines have come a long way since the smelly, noisy oil burners of the 1970s. They get great fuel economy, but now are much quieter, more powerful and about as clean as most gasoline engines.

In 2006, the government required cleaner diesel fuel, called ultra-low sulfur diesel, which in turn allowed automakers to install emissions control devices such as catalytic converters on diesel cars. Other technology, such as high- pressure, common-rail direct injection and turbocharging have boosted power and reduced diesels’ tendency to rattle like marbles in a can.

In addition, any diesel engine can run on biodiesel, a fuel made from the oil of soybeans, rapeseed, or other biomass. These vegetable oils are treated with lye to make them more viscous. The result is a nontoxic, nonexplosive, and biodegradable fuel that burns cleaner than petroleum diesel.

With an additional fuel system and tank, older diesel engines can also run on vegetable oil and even recycled vegetable oil from restaurant fryers, for example.

In some European countries, diesels account for more than half of all new car sales.

Pros Diesels get about 30 percent better fuel-economy than gasoline powered cars and have lots of pulling-power, called torque. Many diesel engines also have a reputation for durability, because they are built with heavier components to withstand higher compression.

Cons Diesels often cost more to buy than similar gasoline-powered models, and diesel fuel is more expensive than regular gas. New models that use urea injection to reduce emissions have to have this system refilled with each oil change. Despite becoming more popular, diesel is still only available at about 30 percent of U.S. gas stations.

For more information on alternative fuels and fuel economy, see our Guide to driving green.