I think in that is also the difference between manufacturers who have improved their engines through efficient design of the engine - I think VW are one of those and it can be seen by how incredibly easy they are to do performance upgrades to and how little fuel they use. I would say there is not a lot between these motors now and one that has been prepared. Others on the other hand I think are not designed as well and they rely on various settings to achieve their targets and in the process make less power, more pollution and use more fuel - these will be the ones who are worried about new standards as they will need to redesign their motors and upgrade their manufacturing processes to comply.
An example. Compare a Subaru WRX motor to one from a GolfR/AudiS3.

