[Phantom]

It sounds like what the dealership is using is similar to GMs TechII that can change some parameters.

Changing the idle speed can be done via a remap on most ECUs and should have a few lines in the table. On the cars (gas) that I have looked at they have the following:

The Y-axis is:
AC off in drive
AC off Neutral/Park
AC on in drive
AC on Neutral/Park

The X-axis is:
Coolant Temp

The corresponding cells contain the desired idle RPM. This way the idle will be higher at low temps drop down at operating temp then rise a bit at high temp to spin the water pump more for cooling. Also it will bump the RPM up a bit when the AC is on.