Engine performance is now dependent on air density/temperature

Yes. You're right...I should do some tests. My question was actually in regards to "real life". Is there a difference between Turbo & NA engine output at rising or lowering air densities in the real world? Sorry for not making that clear.

 

Yes there is, turbocharged engines are less affected by low density air afaik.

 

I can confirm that changing the values under AMBIENT TEMP. does indeed influence the output of the cars engines.
Yesterday I tried to redo some of my earlier hotlap records (made with game version 1.5.9)
but instantly noticed by looking at the the delta displays of several apps (Multilaps_v1.1, RaceEssentials_v1.1 show very detailed momentaneous time differences)
that the time I lost grew rapidly even on the straights.
With the new vehicles from the JDM DLC the delta was much smaller and after some practicing almost at 0.0.
After stumbling over this thread a few hours ago and setting AMBIENT TEMP. to 10 °C I realised that the delta not only changed to green with raising time difference but the speed reached before the braking points was a few km/h higher as well.

 

Must only be partly finished then, one of the changelog items was that temps are no longer static in the shared memory reference. But that doesn't automatically mean they're actually changing.