NGK manufactures many types of glow plugs that feature the latest in technology. Restrictions on automotive exhaust gas emission and the promotion of low pollution vehicles are a reflection of their awareness of the need to protect our environment.Manufacturers of diesel-powered vehicles are hard at work developing new technology designed to meet increasing restriction on exhaust emissions. Glow plugs were originally developed as a method for improving starting performance of diesel engines. Now technology has developed to the point where glow plugs also contribute to the reduction of exhaust gas emissions.