Today we are doing a sim update which includes a reworked dirty air and slipstream effect. Since the last update dirty air was turned off, in the meantime we have been developing a new reworked version for dirty air and slipstream. This has been tested during 2-3 weeks both internal and external.
The results are a weaker dirty air effect and a slipstream which should work in better conditions to make overtaking easier against cars with a heavier fuel load or tyres with noticeably less wear.
We will do a sim cycle so no maintenance window is needed. Once the mentioned changes are fully released, we will post another comment.