Built with durability, reliability, and optimization in mind, diesel engine systems are designed to use their own compression to ignite fuel. In gasoline engines, the fuel is mixed with air, compressed by pistons, and ignited by a spark plug. The rate of compression in a diesel engine is more than three times that of a regular gasoline engine system. In a diesel engine system, the air is compressed at a high compression ratio, which introduces a great amount of heat. Following this compression, fuel is directly injected into the cylinder, where the fuel vapor is ignited. Diesel engines are built without spark plugs. Instead, diesel systems use glow plugs to start and run more efficiently in colder temperatures. Glow plugs have two heating elements that allow them to get very hot very quickly for fast starts. Turbochargers increase the compression ignition by quickly compressing the air flowing into the engine, allowing for more air to flow into the chamber. More air in the combustion chamber means more fuel can be added to the combustion process. Turbochargers provide diesel engine systems with improved efficiency, and ultimately, more miles per gallon of diesel fuel.