This has a single heating coil, the electrical resistance of which does not change as the temperature increases. Therefore the current consumption of this type is constant.

This type has a single heating coil which changes its electrical resistance as the temperature changes. Resistance is low when voltage is initially applied and a large current can flow through the heating coil raising its temperature more rapidly than the standard type. This has the effect of shortening the required pre-heating time. As the temperature rises the electrical resistance increases reducing the current flow.

The Quick Glow System glow plug can raise its temperature quickly but is only used in conjunction with a special QGS control unit. Because the single coil type QGS glow plug has a low resistance, enormous current flows to the heating coil and temperature rises quickly, compared to the standard and fast heating type glow plugs. The design of this glow plug allows very short preheating times and improved starting performance.