Dayton Daily News

Q: What is the difference between diesel fuel and regular gasoline?

A: Diesel models have recently been bumped into the spotlight as "green" for a few reasons. Diesel engines are inherently more fuel efficient than standard gas engines, plus the use of new clean-diesel fuel has significantly improved diesel emissions.

The difference between cars that use diesel compared to gasoline isn't just the fuel itself. A diesel engine is specifically designed to run on diesel and is built differently than a standard gasoline engine.

Both engines work on the basic principle that fuel needs to be burned to create power. Diesel fuel is more resistant to combustion and a diesel engine depends on higher engine compression — which creates heat — to burn the fuel, instead of a spark like in gasoline engines. That higher compression as well as the increased energy content of diesel fuel contributes to better fuel efficiency compared to gasoline engines.

The stigma that diesel needed to overcome was the image of big-rig syndrome. People still associate diesels as noisy and dirty engines that puke out huge clouds of black smoke. The truth is that newer diesel engines don't have those traits at all.

The following is from the Cars.com Green Buying Guide article, "The Return of the Diesel":

"The most important point is that diesels are no longer dirty, stinky or noisy, thanks to new clean-diesel technology expected to hit our streets by the end of this year. They're pretty much as clean as gas engines. What makes them greener is that diesels are about 30 percent more efficient than gas engines of comparable performance.

If you're burning 30 percent less fuel, that means 30 percent less carbon dioxide — a greenhouse gas — produced, which is what typical hybrids deliver. Voila! Suddenly

diesels are green."