It would be great to have a more customisable HUD. Just being able to switch on and off each HUD element would improve immersion. There is no need to have the trophies and target times during time trial for instance (once, prior to the event, is enough), nor is the time of day (does it matter if the time is 13:00 or 14:00?), or the digital rev meter for Premium cars with working dials (fuel gauge is useful though).
Sector delta times would be enough for me in Premiums, less need for all the other stuff!