[highball]

Can you translate that for us non-mechanics?

I’ve rebuilt a carburetor once or twice, but that’s the extent of my expertise.

[RayChuang88]

Here's what I know: on a gasoline direct injection (GDI) engine, the fuel is directly into the combustion chamber, not into the intake air stream just before engine intake valves (this is what's known as port fuel injection). By directly spraying the fuel into the combustion chamber, the gasoline acts to "cool" the air fuel mixture before the spark plug ignites the mix, which results in more efficient fuel combustion.

It also allows the compression ratio of the engine to be raised well above normal, which results in more power and better fuel economy. Unfortunately, this change also increases the NOx gases in the exhaust, which requires wnat's known as a de-NOx catalytic converter. While this works, de-NOx catalytic converters cannot work with gasoline that have more than 10 parts per million of sulfur compounds. With the new EPA requirement that all gasoline must be limited to no more than 10 ppm of sulfur compounds, that makes de-NOx catalytic converters viable, making it possible for more powerful GDI engines with lower fuel consumption.