[RI_RS4]

South.

Okay, I'll give you that. There are multiple forms of 1st, 2nd and 3rd generation Direct Injection, and can be classified as Spray Guided (as you said) and Wall Guided. First generation spray guided systems sucked and never got to market. First generation wall guided systems also sucked, since the fuel was litterally sprayed on the wall. Later generation DI either uses the spray nozzle to direct the flow into the spark plug, placing the injector between the valves and the spark plug (which requires much higher pressure to make sure that intake flow does not disrupt the spray), or the flow pattern in the combustion chamber, combined with the location of the spray nozzle. The spray guided method has a long term issue with intake valve deposits, since detergents from the spray cannot be deposited on the valves efficiently. The wall guided method with tumble swirl flow pattern can be designed to allow some fuel to swirl back onto the intake valves for cleaning. It will be quite interesting to see how both systems fare at 100K miles, since the biggest unresolved issue with all DI systems is intake valve deposits and oil fuel dilution.

All are forms of direct injection. Differences in one over the other only occur in lean burn mode. In homogeneous operation there are no differences, and certainly none at WOT. Thus no advantage or disadvantage of either type of direct injection with respect to top end performance. However, it remains to be seen whether any advantages hold true in practical applications after 100K miles are on an engine. Since you are from Germany, you are fortunate enough to be able to use engines which run in lean mode. I'd be interested to hear how both types hold up. Here in the US, the advantages/disadvantages are nil.

Both BMW and Audi engage in disingenuous marketing in the US. Both tout their HPI and FSI systems for significant fuel economy increases, yet neither use the fuel conservation mode in North America.