Today's diesel engines inject fuel directly into an engine's cylinders using tiny computers to deliver the right amount of fuel. All functions are controlled by an electronic control module that communicates with an elaborate array of sensors placed at strategic locations throughout the engine. These sensors monitor everything from engine speed to coolant and oil temperatures to piston position. Tight electronic control means the fuel burns more thoroughly and delivers more power, better fuel economy, and fewer emissions.

Modern direct-injection diesel engines produce low amounts of carbon dioxide, carbon monoxide, and unburned hydrocarbons. Emissions of nitrogen oxide and particulate matter have been reduced by more than 90% since 1980.