[chittychittybangbang]

http://www.myturbodiesel.com/1000q/Audia48k/2012-audi-A4-tdi-avant-faq.htm

I've had this Audi A4 TDI FAQ for a while...it's total speculation but I wrote it in anticipation of an Audi A4 TDI in North America. They've already got the drivetrain with quattro approved for emissions in the USA - the 3.0L CATA TDI engine in the Touareg TDI and Q7 TDI. They just have to put it in the Audi A4 body.

Also, they stopped making the A4 with the regular V6 engine. You can only get them in 2.0L gas. The next step up is the Audi S4 (sport model) with the 3.0L supercharged gas engine. That conveniently leaves a space for the 3.0L TDI engine - more powerful than the 2.0L gas model with greater efficiency and less powerful and sporting than the S4.

 

[chittychittybangbang]

The next 10 years will be very interesting. Gasoline engines are slowly raising compression and efficiency. For example, Volkswagen released a prototype engine they call CCS, Combined combustion system. It is based off the TDI engine but runs off gasoline. It combines the "homogeneous combustion and low nitrous oxide emissions of a typical small capacity petrol powerplant with the self ignition and low fuel consumption properties of a modern day diesel – the aim being to combine the best attributes of each"

They start the combustion a lot earlier than TDC vs. a diesel but use no spark plug. The earlier injection and combustion helps reduce the NOx and particulate emissions in diesels. Attached are some pictures of the CCS engine. Other manufacturers call it HCCI.