I was able to obtain some more info pertaining to the OP question. Z Taking center stage and the backbone of these technology changes is Gasoline Direct Injection (GDI) and Turbo Diesel Injection (TDI) engine. To review, previous fuel injection models relied on indirect injection of the fuel spray outside the combustion chamber at a stoichiometric ratio of 14.7:1 air-to-fuel. Typical piston compression ratios were limited to about 9:1 in gasoline and 20:1 in diesels due to the limits of squeezing this finite volume of incoming air.
However, Direct Injection has completely reinvented this piece of physics by allowing for more air to enter the engine while reducing the amount of fuel required for ignition. Ultra-lean fuel mixtures as high as
65:1 have been achieved in some models while the average ratios hover around roughly
25:1 on average. This is a quantum leap from the 14.7:1 limit from which we came.
One good example of this new direct injection (gasoline) engine is found within the Ford EcoBoost. The EcoBoost model is well on its way to becoming the most popular engine in its class. The 3.5L EcoBoost achieves an impressive 355-365 hp @5700 rpm, and 350 lb·ft torque, and delivers power like no other. It contains some truly impressive engineering innovations.
From twin variable turbochargers spinning
at 170,000 rpms to fuel injection pulses varying from low-pressure ultra-lean micro droplets to richer
3,000 psi squirts, this engine can make gobs of power at the mere touch of the pedal. Even the pistons have a specific concave indentation, to facilitate high turbulence within the combustion chamber for optimum fuel-air mixing.