What is GDI (gasoline direct injection)?

GDI (gasoline direct injection) is a method of fuel injection used by some modern petrol engines. Direct injection has been commonplace in diesel engines for years but has only relatively recently been used in petrol engines as injector technology has improved. As the name implies, gasoline direct injection atomises petrol directly into the combustion cylinder. This is distinct from older multi-point injection systems that indirectly spray fuel into the intake to mix with the incoming air before it gets sucked into the cylinder.

Direct injection gives the engine slightly better control over exactly how much fuel is used at any given moment, which can improve performance and efficiency. It's worth noting, however, that the benefit over multi-point injection is fairly small, so some modern engines still favour multi-point injection – or a blend of direct and multi-point – while seeking out efficiency gains elsewhere.