Common rail is nothing but a direct fuel injection mechanism designed for diesel and petrol powered vehicles. The engine powered by gasoline uses the technology of gasoline direct injection mechanism. On the other hand, engines powered by diesel uses the high pressure direct fuel rail system that feeds individual solenoid valves. The high pressure goes over 1,000 bar or 15,000 psi or 100 MPa. With the technology, this technology has also advanced very much. The third-generation common rail system for diesel engine comes with piezoelectric injectors that provide improved precision. The pressure in new common rail injectors is over 3,000 bar or 44,000 psi, or 300 MPa. This technology is suitable for all the engines are powered by diesel. It can be used in regular cars as well as heavy duty vehicles like truck, trailers, etc. The major suppliers of the modular common rail mechanism are Delphi, Robert Bosch GmbH, Siemens VDO and Denso. Every manufacturer using this technology derive this with different names such as VCDi, CDI, CCR, i-DTEC, CRDi, DICOR, dCi, etc. The piezoelectric or solenoid valves put together a fine electronic control on the fuel injection quantity as well as time and higher pressure. As compared to the old technology, this new technology also reduces the noise of engine, vibration of the engine and emission of smoke by limiting the necessary fuel injection to the engine. Those days are gone where diesel vehicles were emitting too much of black smoke from the exhaust.