I believe what I was looking for is called Direct Fuel Injection (DFI), which appears to be a method of injection that is more advanced than Electronic Fuel Injection (EFI).
According to Porsche:
Porsche made the move to direct fuel injection (DFI), the first major revision to the sports cars injection technology in 40 years. DFI, as the name suggest, injects the petrol straight into the combustion chamber, leaving pure air to be fed through the intake manifold.
Mercedes-AMG has developed a new high-revving, naturally aspirated 5.5-liter V8 engine (M152) featuring the AMG Cylinder Management cylinder shut-off system. Although peak output in the new engine increased by 60 hp to 415 hp (309 kW) and torque increased from 376 lb-ft to 398 lb-ft (540 N·m) compared to the existing AMG 5.5L V8, fuel consumption is about 30% less.
The AMG 5.5-liter V8 engine with AMG Cylinder Management and direct fuel injection will be applied exclusively in the 2012 SLK55 AMG, which will debut at the International Motor Show (IAA) in Frankfurt/Main in September. The SLK55 AMG will remain the only roadster in its segment with an eight-cylinder engine, Mercedes said.
The new M152 engine is based on the AMG M157 5.5-liter V8 biturbo engine which first debuted on the 2011MY CL63 AMG and S63 AMG. Numerous components and systems are basically identical, e.g. the displacement, bore/stroke, distance between cylinders, ECO stop/start system and direct injection technology. Distinguishing features versus the M157 include new intake air ducting, new cylinder heads, the modified valve drive, an adapted oil supply system and an optimized crankcase.