High Precision Injection and Twin Turbo
Two milligrams of petrol - that's how precise the High Precision Injection (HPI) controls the fuel-air mix. The dosage of the fuel injected is precisely ensured by the piezo injectors with only part of the combustion chamber being filled under lower partial loads. Thanks to the Twin Turbo, it is now possible for the straight six-cylinder engine to provide a supreme standard of power and performance previously only conceivable with far larger engines. Engine weight is also much lower, inter alia on account of the all-aluminium crankcase, which naturally benefits the agility of the entire car and offers more power on less fuel.
in the BMW Z4 Roadster.