Technology Showdown: Diesel vs. Gasoline

Stephen Pope

Tuesday, October 29, 2013 at 12:11 AM ET

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Key Takeaways:

Diesels rely on glow plugs for cold starting and high-pressure fuel injectors due to the absence of traditional ignition sources.
They produce less horsepower but significantly more torque (three to four times) compared to gasoline engines of the same displacement.
Diesels emit fewer greenhouse gases, including carbon monoxide, hydrocarbons, and carbon dioxide.
Their higher fuel energy density and improved efficiency lead to better economy, though they are heavier due to the robust casting required for higher compression ratios.

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1. Because they lack an ignition source (i.e. magnetos and spark plugs), diesels incorporate glow plugs for cold starting. Heat from compressed air ignites the fuel-air mixture.

2. Diesels must use high-pressure fuel injector nozzles to pump fuel directly into the cylinders. The injector has to be able to withstand the temperature and pressure inside the cylinder and still deliver the fuel in a fine mist.