Oettinger use recalibration of the engine management - via Directport - utilising the cruise control stalk
Also see here http://www.goapr.co.uk/remaps.html
The APR site goes into a bit more detail and uses the same functionality as Oettinger and also can add different maps to suit 
Hmmm - APR.
There were/are issues around all of the US based chip tuners, which APR are (ohh, that sounds pants!) one. Basically, because the US has lower quality fuels than here in the UK and Western Europe, on FSI engines, the "S" bit of FSI was disabled. The "S" bit is the "lean burn" mode, used for fuel economy during light/part throttle. During this mode, instead of the fuel mixture being stoichometric, ie, a ratio (by mass) of 14.7:1, the fuel mixture is homogenised, or "stratified". No US based chip is able to include the homgenised component in their map, and so fuel economy will suffer!
This is one of the main reasons why I would personally recommend using only a UK or German based dedicated VAG chip tuner, which would include either REVO or Oettinger!
